R 22

Rhodes 22

 

Depth Finders & Installation

I purchased an r22 from stan this summer. we trailer sail on lakes only. after 4 times out now i can be in the water in one hour from the time we get to the lake to parking the trailer. and that is all by myself, paula prefers to read while i ready things. not too bad, really appreciate that mast winch.

because we sail inland lakes only, i'd like to install a depth sounder. most of the lakes are 40' to 60' max. we sail into coves occasionally for a swim or to anchor for the night and it would be nice to know just how much water there is under us. in the future i may consider adding a knotmeter/log. i'd really like to think about adding a whole system; depth, wind, speed, log, gps and whatever but just can't justify the cost of that. my question is the installation of the transducer. drilling a 1" or 1.5" hole in my boat on the bottom is a little worrisome. just how thick is the hull? what is the best location for the transducer? anyone with experience with a transom mount transducer vs. a thru-hull? each instrument means potentially another hole, any limit to the number of holes you can punch in an r22?

then how about the location of the instruments themselves. the obvious location is the outside cabin wall. but then the instruments are on one side or the other and may be a bit harder to read when on the opposite tack. anyone ever put instruments in the center below the cabin doorway? i haven't installed a compass yet and was thinking this might be the best location.

while we're discussing instruments, i'm sure its been asked before, but what are some experiences with various mfg.? i've put raytheon at the top of my list for now. but have not had time to look into the possibility of a fancy fish finder with depth, speed, log and temp. it sounds like a reasonable alternative to several gauges. maybe i could even get one with gps! anyone using a fancy fish finder, and do you call it a fish finder or does it become a multi-functional electronic nav aid on a sailboat? just wondering.

Unsigned


for a thur-hull, a good spot is center line in the lazzerret, the fishfinder is about 1/3 to half the price of the sailboat depth/speed, transom is cheap and works and cleaning better. wind is over prices (your money), stick to one brand, if you are going to add a auto- polit that make it a chose of navico or apleco.

MJM
26 Sep 1998


The knotstick is available at West Marine for 39.95. Serial #140228

TightHead
26 Sep 1998


I purchased a cheapy depth sounder and fish finder from wal mart for about 100.00. The Transducer can be either mounted on the transom or you can expoxy it in side the hull. When you use the proper epoxy the fiberglass might as well be water the transducer goes right through it. Oh it is a Hummingbird depth sounder. I decided to do the transom because I was worried about the keel being in the way of the transducers deflection. But when you monut it on the transom, as I found out, the transducer pops out of the water when I heel to the opposite side. I think if i was to do it again, or when I take it out of the water I will locate it inside the hull in the aft compartment. To test this out before you install it, put some water in the bilge and the transduser will see right through the fiberglass. then epoxy it in to the manufactures specs.

JTonjes@aol.com


to answer your exact question, call the manufacture and get the instruction book, that should help allot.

I tried to put something together, but I failed very much going off the deep and covering the only a small part of the subject. I scraped that knowing that a book is needed (or a better writer then me :-) and pictures would help.

A very simplified version (as in a lot of the details are missing)

  • The Display head: the thing in the cockpit that you see the numbers on. most likely has the "brains".
  • transducers: think of it as converting a physical measurement into a electrical measurement, their is usually an adjective describing what type of transducers it is, for example "speed transducers", "temp transducers" "depth transducers" "compass transducers" "wind speed transducers" etc....
  • Biducers: transducers that has 2 functions built into one unit, for example "temp and depth transducer"
  • Triducers: transducers that has 3 functions built into one unit, for example "speed temp and depth transducer"

How depth is measured: a sound wave is sent out by the transducer and the transducer listens for the echo, by measuring time you know the depth.

How speed is measured: this transducer uses a paddle wheel that turn based on water passing over it, the faster is moving the faster the paddle wheel turns, by using time your know know the speed.

How is temp measured: this transducer is acting like a thermonitor.

these transducer need to contract the water to work, that where there get the name thurhull or transom mount.

The are connect to the Display head(s) with a cable(s).

The display heads can combine their information together, that is call interfacing, some of the name are "seatalk", "corus", and nmea 018, they can also be connected to radars, gps's etc....

I hope this helps a little.

MJM
12 Nov 1999


I concur. GB maounted both my depth sounder and speed log in the lazaret. So far there's been no problems. There's another possible advantage to this location. If enough stout folks loiter on the bow, the stern may lift high enough to raise the sending units out of the water for maintenance. Also, GB made a very nice teak cover for the sending units in the lazaret. It protects them from all the junk I keep in there.

Bruce Chisholm
s/v Compass Rose
09 Nov 1999


If I was going to get a "sonar" unit, I would skip the plain old fishfinders that tell you how deep it is under the keel and show you cute little fishies, I would jump for the real deal. I think Interphase makes several units that are actuallly forward scanning and side scanning sonars. They show you the depth under you and give you a picture of the area forward of your position. You can see if things are lurking in your path that you might not want to hit. They make two models, one that is forward scanning and one that is side scanning. It would be nice if you could get both units in one box so you could see what's ahead and what's on each side.

The cost of these units are a bit more than the plain ole fishfinder, but the usefulness is a bit greater. As to the knotmeter, you can get any number of units, some of which are self powered, that give an accurate picture of your forward progress. We have the Autohelm bidata unit that gives depth and speed and will be changing that out for the same kind of unit made by Standard Horizon so that the wind indicator we purchased will talk to the knot/depth unit. Autohelm units communicate in propietary Seatalk network, not the NEMA 083 or whatever standard everyone else uses.

Alex Bell


my best advice is spend the money for the tri-data, the cost is not as different because you have to replace the transom transducer(but still 100-200$ depending on make), It one of those subject that look right on paper but do not work out in use (like the mac26x), I went with the fish finder and a transom mount, it was a mistake, the nav information is small and hard to read from the tiller and the transom is a lousy place speed/depth reading on the boats, heal and turbulence screw it up. the only real advantage is it easy to clean their, but a self sealing transducer mount one will help that problem. Their other thing I am sure you are thinking is while the price difference, the bottom line (and the companies admit it) is that they can get it from the sail boat crowd, it hurts, A good pick on using defender and an other tick is that west marine will price match defender ( just give them the catalog page) and they are less prone to screwing up and take return a little better.

MJM


My name is Bob Vine and have just rejoined the list. I have sent Stan a deposit for a Recycled Rhodes 22. I am looking for some advice as to what options I should add prior to shipment ( no pun intended). I took the demo sail with Stan this summer and let's say it was an adventure. Stan is quite a character.

Stan is a purist and just wants a basic sailboat. I am considering adding a depth sounder. Stan says don't waste the extra bucks. What are your thoughts?

thanks

Bob, Atlanta, GA
24 Nov 1999


A depth sounder can be used for navigating if it is accurate, you know the condition of the tide and have an acurate chart. If you can only get a bearing on one object, instead of doing a running fix, you can plot the bearing and use the depth to determine your point along the line.

Gene Osias
23 Nov 1999


I'm with Stan.

The Rhodes will sail in roughly 2 feet of water. Few depth sounders can measure depths that shallow.

If you are sailing in less than 2 feet of water you really ought to know it without the benefit of a gadget, and, about the last place you should be looking is your bulkhead. You've got bigger problems to deal with than determining if your depth sounder is really accurate to a tenth of a foot.

Few depth sounders look ahead. Most simply tell you what you are over right now. And right now is too late if you are moving.

Most depth sounders are also inaccurate when you are heeling. Using a depth sounder to determine anchor scope introduces unnecessary complications. Scope is calculated from a point above the water line. Depth sounders calculate depth from a point below the water line. Few people know the vertical distance from the measurement point below the water line to the tethering point above the water line. Since the calculated depth is multiplied by 7 to determine scope, this error is also multiplied by 7.

Most of my friends turn off the alarms on their depth meters. They are constantly sounding false alarms.

I use a lead line. Simple. Reliable. Accurate. I've noticed that when the going gets tough, friends with depth sounders break out their lead lines, too. When push comes to shove you can trust a lead line.

I have marked depths on my anchor line. Makes it simple to know anchoring depth. Multiply that number times 7 for your scope.

Bill Effros


If you want a depth meter installed, it doesn't require a hole in the hull to be installed. It can be placed in the lazerette without any hole in the hull. Depending on placement, all wires can be run under the seats thru existing pass thru's.

Rummy
24 Nov 1999


Of course, a depth sounder will require two more holes in your boat --one for the instrument and one for thhe transducer. I have a strong resistance to cutting such holes--the bulkhead compass was about as much as I could tolerate. But other people can cut with abandon and feel no ill effects! Once you can tell the depth, you will probably feel uneasy when you don't know it, so you will probably be tempted to glance at the instrument quite a bit. Eventually, you will likely find it more interesting to look at the sail trim, or other boats, or whatever, so you will begin to ignore it.

The sunlight glinting off of it will make that even easier to do. You will get cocky with the centerboard up: "I can go anywhere." Then one day, as I did not too long ago, you will want to save a tack and cut a point too close and begin to run aground.

Fortunately, the bottom where I sail (Chesapeake Bay) is usually mud, so I just hopped out and shoved the boat off before we really got stuck in the goo. If you will be sailing where the bottom is hard and depths vary quickly or dramatically or unpredicatably, then a depth sounder might be a very prudent accessory. Or maybe you just want to know the depth and that's that!

I ended up with a little handheld, battery powered depth sounder, which so far has worked just fine. I have used it mainly to judge anchoring depth and set proper scope, and also have checked depths a couple of times when we were not sure of our position relative to shoal areas. You just stick the end of it in the water, press a button, and get the digital readout to the tenth of a foot. Not cheap (about $150) but easy to use, accurate, much less expensive than the installed version--and no holes required. I figured I'd give it a try and if I still wanted a real depth sounder, I'd install one. So far, I haven't felt a need to do that, though I have been glad I had the ability to determine depth when I needed to.

I miss a knotmeter more, but have also found the trailing knotstick (about $30) to be quite effective so long as I take care to keep it away from the crab pots. The knotmeter is interesting because it gives you a message about various sail trim/sail plan configurations, and decent speed estimates are essential to dead reckoning. After a while, though, you can get pretty accurate at judging speed, however; I can usually come within a couple of tenths of a knot just by the feel of the boat, sound etc., so I don't use the knotstick as much as I once did.

One thing's for sure--I'd add a bimini long before I installed either a depthsounder or a knotmeter--but I'm sure there are plenty of people who would have precisely the opposite opinion.

David Dawson
R22 Ardent


What is the best location to install a depth sounder on the Rhodes? Any experience with using an internally mounted (no through-hull) unit?

Bob Bernard
s/v Second Thought
06 Sep 2000


For those who have installed their depth sounder transducers forward of the shoal draft keel:

Do you ever lose your bottom return echo signal when the boat is heeled way over on the side opposite to the depth transducer?

The hull has a very pronounced V shape up forward of the shoal draft keel and the depth transducer can only send and receive signals within a certain angle or cone (usually 20 deg or 36 deg depending upon make & model). With the depth transducer installed at an angle to the bottom because of the V hull shape & then tilted over 20 or 30 deg more due to heeling, I would worry about losing the bottom return echo signal when heeled over.

Before I installed my depth sounder, I called up Stan at GBI to find out where the factory installs their depth sounder transducers. Stan recommended the location closer to amidships in front of the icebox.

The hull has much less V shape amidships, so the transducer is more nearly perpendicular to the bottom. My depth sounder works equally well on both tacks. Maybe I'm just worried about nothing here, but it's something to think about before you cut the hole in the hull.

Roger Pihlaja
S/V Dynamic Equilibrium


I can't tell you which is the BEST location, but I've been very happy with ours. It is on the port side under the step to the v-berth. It is directly opposite the speed transducer, which is under the Porta-potti. It is roughly even with the leading edge of the shoal keel and it is still relatively flat. So far, I haven't detected lost signal for any reason. It is far enough forward that it does not get bubbles from the keel, and should let me know of an obstruction just before I hit it, instead of just after I hit it. Maybe I have lost signal in big gusts, but I'm never looking at the depth sounder then, so I'll never know. Roger's location is probably good, too. Just make sure you get clean water around it, and protect it from potential damage in the bilge. I like the idea of having it forward, but that is probably irrational. I probably don't really have any more warning than anyone else. Maybe someone else has had a problem with it in this location? If so, I hope they'll chime in before you drill!

Doug Gardner


I am planning to put a depth sounder on my '89 R22 and would like to ask a couple questions of those who now have one installed:

  • 1. Where is your transponder installed and what type is it--transom mount, thru-hull or puck?
  • 2. Is the R22 hull bottom of a core design? If so, do you know the approximate individual thickness of the inner and the outer fiberglass as well as the wood core?
  • 3. How far forward and how far to the side does the ballast extend? (Use as a reference point the point at which the forward end of the ballast fairs into the hull bottom.)

John Seymour,
high atop Lookout Mountain
23 Mar 2000


My transducer is a thru-hull type, Autohelm ST-50 series. It is mounted amidships on the starboard side of the hull as close as possible to the shoal draft keel. I installed a 4-inch diameter s crew-in inspection plate in the cabin sole for access to the back side of the transducer. The hull is solid fiberglass there, approximately -inch thick. Inside the cabin, the inspection plate is right in front of the icebox door. The transducer ends up being about midway between where the keel flares into the hull and where the hull rests on the trailer bunks. You want to be as inboard as possible because resting the mass of the boat on top of the transducer when the boat is on the trailer would be a really bad thing to do!

The other option is a thru-hull type transducer back in the lazarette compartment, as far forward in the compartment as possible to prevent bubbles under the hull from killing the acoustic echo signal. However, I would protect the backside of the transducer with some sort of HD cover and run the cable inside a well-secured conduit. You never know what might be banging around inside the lazarette compartment.

I don't recommend the transom mount style transducer.

Roger Pihlaja
S/V Dynamic Equilibrium


Our new Rhodes 22 is being built and we need some advice on a depth finder. I asked Stan but he said to ask the list. We will be sailing in Maine, in the Harpswell area. After visiting West Marine and looking at what they have, we think we like the Horizon DS 30. Any advice? In any event, do we get flush mount or bracket?

Thanks. Pam
12 Feb 2001


We Bulldoggers have a combination unit. Lowrance:GPS, ChartPlotter, knot meter, fish finder. Mount it in the cabin over the galley when not in use, and have extra cord so we can take it out in the cockpit to velcro it. Don't know if you need all this equipment for your uses, but for us it works great. We were able to purchase it over 100$ less from a local dealer then from Boat US or Defender. Unit was around 350-400$

William Barry
12 Feb 2001


My R22 came with an Autohelm ST30 Depth Finder and an ST30 Speed Log. Both have been working fine. Other folks have installed Autohelm ST50 units, primarily because they wanted to connect other things like GPS, chartplotters and wind speed.

As to bracket or flush mounting, it's harder to get sheets and halyards tangled around a flush mounted unit (but if you try real hard...). Anyway, my ST30s and my compass are flush mounted on the cockpit bulkhead.

Gary Sanford
S/V Raven
Syracuse, NY
12 Feb 2001


We have had the Autohelm/Raytheon ST30 multi/bi data on Blew Daze, and I pulled them off and replaced with Standard Horizon MD-100 knot meter and depth sounder. They work well. So did the Autohelm ST30, but I wanted the wind speed/direction instrument and did not like the AH 30 series display. For an economical electronic wind speed/display, the Standard Horizon display is much easier to read and interpuit.

Adding the Horizon Wind to the Autohelm system was not an option. They were not exact matches and not connect to each other. When you add input from your knotmeter to the wind system, it can give you apparant wind speed and direction as well as true wind and direction. That's the reasoning behind replacing the ST30 instruments.

BTW, I would go with the multidata because it gives you both the knot and depth in one nice readable display.

Alex Bell
13 Feb 2001


I have a Nexus Combination Depth and speed (also water temp). It's mounted in the cockpit on the starboard bulkhead. Larger numbers than the autohelm.

Like it a lot. Installed it myself.

Bill Berner
13 Feb 2001


I've got a Horizon depth-knot-temp combo that works great. Don't remember the model name off the top of my head. Transducers are just in front of the keel. This unit gives 2 readings simultaneously, and each can be set to read speed depth, temp, avg speed, and all kinds of other stuff that I don't use often enough to remember....

Brian
13 Feb 2001


For what it worth, I really like my ST60 tridata and the new ST40 looks like a nice unit from what I read.

MJM
14 Feb 2001


Stan is working on our new R22 and asked us where to install the depth finder. When I didn't have an answer, he suggested I come to the list. SO, here are our 4 options:

  • 1. on an arm mounted inside the cabin on the bulkhead. The arm would swing out into the companionway when the depth finder is being used. Disadvantage: the wires are "loose."
  • 2. on the side (outside) of the lazarette. The captain can then look DOWN on the face of the d.f.
  • 3. on a bracket mounted on the same panel (removable) as the compass. The bracket enables the face to swivel. The three plugs would have to be plugged in/unplugged each time it's used.
  • 4. flush on the bulkhead wall in the cockpit. He would put it to the side so that it wouldn't be in the way of "loungers."

Any input would be great. Thanks.

30 May 2001


Most owners have found the port bulkhead as the most convenient location for electronics such as depth gauges, knott meters, compass and wind instruments. There are covers which can protect and conceal the hardware inside the cabin.

Rummy
30 May 2001


I think the stbd side bulkhead is a good location. Here's a link to a picture of one installation.

http://www.michaelmeltzer.com/rhodes/pics/Saroj_Anne.jpg

Mine is in roughly the same location and was done by the previous owner's boat yard.

You want it where the skipper can see it when underway. Most d.f. units come with a cover to keep out the weather.

My own 2 cents is that the compass should be on the port side bulkhead, not on the removable board. I found it to be a favorite trip hazard and am happy with the bulkhead mounted compass I added last year.

Gary Sanford
s/v Raven
Syracuse, NY
30 May 2001


I agree with Gary. I think the best place is on the bulkhead, on the oposite side from the compass. the picture he referred to shows a great location. I wish the previous owner had mounted my depth instrument there and the compass on the other side. See http://www.michaelmeltzer.com/rhodes/pics/FNSpin2.jpg for the current arrangement on Fretnaught. There are a couple of problems with Fretnaught's current arrangement:

  • 1) Compass too close to the speed/depth for my comfort (I'd like the compass on the port side so I could mount the VHF inside the cabin on starboard side)
  • 2) Speed/depth display is too far to starboard, and is sometimes blocked by crew. I like Glen & Dorene's location much better (see Gary's pic).

Of course, there are good points and bad points of each option. I'll try to identify a few inline with your questions....

30 May 2001


As I see it, you have one good option and 3 rather poor ones. The bulkhead is the only reasonable location where helmsman and crew (hate to use the title "captain" on such a small boat", can see the depth. On occasion, the crew seems to be watching this a bit better than the helmsman, or at least I have found that to be true. The bulkhead affords easy viewing for anyone still upright without concern for wires, brackets that can become an obstacle to cabin access, etc. Viewing angle needs to be taken into consideration with LCD displays too.

I would suggest that you purchase a Bi-Data or Multi-data unit. This would show depth on one line of text and a second line of text would show boat speed. Our unit also gives water temp, as most do. A knotmeter can be very useful as a training tool. You can see what your sail adjustments have accomplished in the form of boat speed.

Alex Bell
30 May 2001


I bought my boat used, and the instruments were already installed. They are a compass, a depth sounder, and a level meter. They are all located on the forward port cockpit bulkhead on the slanty part. I don't use the depth meter much, except for occasional navigation by contour lines, when there is an exceptionally low tide, or when I'm entering an unfamiliar harbor. It is OK where it is. The compass, on the other hand, gets blocked by people sitting next to it. It is not the best location, but I had to replace it once with another of the same brand since the hole in the bulkhead is both irregular and enormous. MAKE CERTAIN that your compass is designed to be read from where you'll be reading it. My first compass was designed to be read from above, looking down into it, but it was mounted ABOVE seated eye level. It was not useful at all. After repair, it has been moved to the proper location in another boat. As far as the levelometer goes - who needs it? But the cosmetic effects of removing it motivate me to keep it.

I hope this has given you some insight toward making your decision.

Dick
30 May 2001


On the BULLDOG we have a combination unit, Lowerance Map 160, which is a GPS Map + SOUNDER/FISH FINDER. We mounted it on a bracket on the starboard cabin bulkhead outside and just above the starboard storage drawer inside. Stan & Company custom designed it for us. We have no holes in the deck at all. He can explain it to you.

Russ
s/v Bulldog
30 May 2001


On BlewDaze, the electronic instruments are located on the stbd bulkhead, close to the companionway, so as not to interfere with the great cockpit seating backrest when sitting facing aft. This seems to work well, easy to view for skipper and crew . . .

We have a clinometer located on the centerline, on the face of the 'tray' just under the companionway opening. I installed the model that has gross readings, as well as a different scale that reads +/- 5%. This is helpful when doing fine tuning with the sails and weight to measure effect. It's difficult for me to envision a clinometer mounted off to the sides - wouldn't the readings be corrupted when not on the center axis?

Currently, our compass is mounted on a board that slides into the companionway guides. It's not convenient for us, so consequently is not frequently used. Now that we're sailing in an area where maintaining a compass watch is more important, I'd like a more efficient compass location. It's fortunate our electronic instruments are installed on the stbd side of the cabin bulkhead. Our vhf and sound system are also located on the stbd side, in the aft-end of the cabin, over the galley. This leaves the port side available for a bulkhead-mounted compass, with minimal interference. Just another thing to add to the 'to-do list'.

Regards, Pamela
30 May 2001


SO, here are 4 options:

  • 1. on an arm mounted inside the cabin on the bulkhead. The arm would swing out into the companionway when the depth finder is being used.

    Disadvantage: the wires are "loose." Loose wires are the weak link in these installations. Having a movable installation will tend to fatigue the wire, chafe the insulation, & loosen the connectors. Depending upon the design, the movable arm may tend to be in the way as well.
  • 2. on the side (outside) of the lazarette. The captain can then look DOWN on the face of the d.f.

    Actually not a bad location. The helmsman is usually seated sufficiently far forward to be able to read the instrument. I would protect the backside of the instrument against shifting cargo inside the lazarette compartment. Consider protecting the front of the instrument face against accidently being kicked as well.
  • 3. on a bracket mounted on the same panel (removable) as the compass. The bracket enables the face to swivel. The three plugs would have to be plugged in/unplugged each time it's used.

    See #1 except 3X more possibilities for problems. Where does the panel live when it's not being used? Is it in the way when it is being used?
  • 4. flush on the bulkhead wall in the cockpit. He would put it to the side so that it wouldn't be in the way of "loungers."

    This is the way my instruments are mounted. My compass is on the starboard side of the companionway. I have an Autohelm ST-50 Tri-Data on the port side. Most people lean back on the cockpit seats. Therefore, to be out of the way of loungers, you want the instruments mounted as close to the companionway as possible. Never the less, you will occasionally have to ask a lounger to move. Good visibility from the helm station, no loose wires, easy to get at the backside for maintenance, not likely to be kicked from the front, easy access to the controls on the front of the instrument. Protect the backside of the instrument inside the cabin with a cover to protect the connectors & for appearance sake. Probably the best option, all things considered.

Roger Pihlaja
S/V Dynamic Equilibrium
31 May 2001


SL45. I have the LED readout screen with a row of four (Keys) below; Speed, Temp Trip and Time. I have the thru hull paddle wheel.

  • 1. Press and hold down the Speed key while turning on the unit. This puts it into simulation mode. It will run randomly through the numbers. To turn off simulation, turn off the power, press and hold the Speed key and turn on power. The display will revert to "0" or "0.0".
  • 2. Turn the unit on, press and hold Speed key for 3 seconds. This will allow you to set the readout in MPH or Knots.
  • 3. Press the Temp key and hold for 3 seconds, set temp in F or C scale.
  • 4. To switch between trip log and permanent log press Trip button
  • 5. To reset trip log, press and hold the Trip key AND Time keys for 5 seconds
  • 6. 5 Minute countdown timer, Press Time key TWICE to access the timer. Press temp key to start countdown.
  • 7. To vary the intensity of the readout, press and hold Temp key and Trip key for 3 seconds. Succeeding depressions of the Temp and Trip keys will scroll the display
  • 8. SPEED LOG Calibration (say using GPS) Press Temp and Trip key together while in Lamp mode. To adjust the speed shown, press Temp or Trip key to change numbers up or down.
  • 9. Press Temp and Trip key while in temperature mode. Press temp key to switch between tents and hundredth decimal point for speed display. Press Speed key to exit

Hope this helps some.

Paul in Atlanta
16 Jun 2001


I've been thinking about depthsounder installation and transducer location. I didn't see anything about this in the FAQ, but recall having discussed it on the list.

I've never been a fan of transom mounted depthsounders, but they are quick and easy, and usually cheaper. I recall some have mounted them inside the cabin, potted in epoxy and shooting through the hull, but where did you do this? What type of trasducer did you use (e.g., does it make a difference whether you mount a trasnducer intended to be transom-mounted or through-hull in this manner? Are there portions of the hull bottom that are less-suitable for thie (i.e., cored)?

Ideally, I would like to mount a relatively inexpensive transducer somewhere forward of the keel in a safe location in a locker or beneath the deck. I would also like to keep it simple and inexpensive.

BTW, on my last sailboat, I used the keel as a depthsounder. I figure the R22 deserved better.

Jim Connolly
17 Feb 2003


There are several options, and each has good points and bad. I don't consider myself the expert on the topic, but I'll give it a shot.

First, I have 2 through-hull transducers: one under the potti, which places it starboard of the keel, near the leading edge. The other is in the same location, but on the port side. The first is the impeller for my knotmeter, and the latter is the depthsounder. Plusses: good clear water (no turbulence from the keel), forward location (there is at least some chance of detecting the rock before you hit it), relatively easy access, but well protected. Minuses: depth reading may be more affected by heel than a centerline mounting, leakage possible when you drill a hole through the hull.

Some have reported good luck with the transducers mounted in the lazz. Plusses: easy to access, flat mounting Minuses: aft of the keel (potential for turbulent water, although none have reported problems, also NO chance of avoiding that rock BEFORE you hit it)

Others have reported favorable results mounting the transducers beside the keel, but farther aft than mine. I think Alex mounted Blew Daze's about even with the companionway hatch, if I recall correctly. The hull is a bit flatter there so should be less affected by heel than my location, and the water flow should be relatively smooth, if you're using an impeller on the depthsounder.

Also, there are the transom mounts. Good news there is they are cheap, easy to replace when you knock them off, and there are no holes below waterline.

OK, now there is the question of cutting a hole or not. There are several ways to mount the depth transducer without cutting a hole. The first is to buy one specifically designed for that installation and follow the directions. The second is to epoxy it to the inside of the hull, as you described. The third is to rig up a fancy oil-filled mounting using PVC pipe fittings. I think I read about that one in Sail magazine, and could probably locate the article with enough time and a specific request to do so. It seemed like an awful lot of trouble for little gain, to me.

What would I do if I were to do it over? I think I'd still put it at my current location, but I'd seriously consider getting a transducer designed to work through the fiberglass. The R22 hull is not cored, but it is thick. Also, you need to make sure you are far enough off of centerline that you don't go through a thick area near the keel.

Just a couple of pennies worth of opinion.

Doug
s/v Fretnaught
17 Feb 2003


Jim, I mounted a fishfinder/depth finder transduce in the most forward part of the laz shooting thu the hull. There is a drain hose there which kinda protects it from getting knocked dont know if the cockpit drain and air bubbles effect it or not - there always seems to be a fish right on the surface :).

Hope this helps.

Bob
18 Feb 2003


The lazarette compartment would be my 2nd choice for mounting a depth sounder transducer. The hull is nice and flat back there. The hull is relatively thin under the lazarette compartment and there is easy access to the backside of the transducer for initial installation and any future repairs. If you mounted the transducer slightly off the centerline; then, any bubbles from the cockpit drain shouldn't affect it. I would mount it on the starboard side away from the engine and as far forward in the lazarette compartment as possible. This is so, that in reverse gear, the bubbles from prop cavitation and engine exhaust won't confuse the depthsounder.

My only caution about a lazarette compartment installation is the need to protect the backside of the transducer and the cable from shifting cargo. I don't know about you; but, I keep some pretty heavy gear like anchors, chains, shore power cord, fishing tackle box, trolling motor battery, etc in the lazarette compartment. On a rough passage or trailering down the road, having one of those items snap off the transducer or damage the cable would be a real bummer. You might lose your depthsounder just when you really need it. Or, even worse, create a bad leak into your lazarette compartment.

The other nice thing about the bilge installation I suggested in my earlier post is that there is nothing rattling around loose underneath the cabin sole to damage the transducer or cable.

There are enough things that can go crooked while sailing. I just hate to install a built-in "gotcha" in my boat that I always have to be careful about. But, I suppose if you were willing to install suitable protection for the backside of the transducer and cable; then, the lazarette compartment could be a good location.

Roger Pihlaja
S/V Dynamic Equilibrium
18 Feb 2003


When I installed the depthsounder on Dynamic Equilibrium, I had many of the same questions as you. So, I asked Stan at GBI for his recommendation re tranducer location.

As per Stan's instructions, I mounted the transducer on the starboard side just inboard of the ice box as close as possible to the keel. The inboard edge of my depthsounder transducer is tangent to the point where the hull shape transitions from the flat "garboard" area to the tight radius fillet to form the vertical keel. I wanted to have quick access to the backside of the transducer. So, I mounted a 6" diameter Beckson screw-in inspection deck plate in the cabin sole right above the transducer. My transducer is a thru-hull installation. So far, the installation has been absolutely bulletproof & has never leaked a drop. I never lose the bottom return echo signal on either sailing tack + it always stays submerged in bubble-free water. The transducer is located well inboard of the trailer bunks. I've never had a depth sounder transducer/trailer interference problem while trailering the boat in dozens of launches/recoveries & thousands of trailering miles.

There is a couple of fundamental problems with mounting locations up forward of the keel, like in the head area. The R-22 hull has a pronounced deep-V shape anywhere forward of the keel. Echo sounder transducers do not transmit & receive outside of a fairly narrow cone. If you mount one of these transducers on an angle, such as would be required up near the bow, it may work fine on one tack or while motoring in level trim. But, when you get over onto the opposite sailing tack & the hull heels over, the transducer will probably lose the bottom return echo signal. The hull shape in Stan's suggested location is much flatter & thus is not subject to this affect. In addition, the water flow over the transducer is much more likely to have entrained bubbles when mounted close to the bow, especially on the sailing tack wherein the transducer is lifted closer to the surface of the water.

There is only about 6' of hull separating possible mounting locations forward of the keel & Stan's recommended location. Anyone that thinks such a short distance is going to keep them out of trouble in rapidly shoaling water doesn't know how to properly use a depthsounder. At 4 knots, the 6 foot forward mounting location translates to about 0.9 sec extra warning time! Of course, the transducer may not be getting a bottom echo return signal, so you may not get any warning at all. I'd much rather have an absolutely reliable transducer mounting installation than worry about such a trivial amount of potential extra warning time.

Roger Pihlaja
S/V Dynamic Equilibrium
18 Feb 2003


Underneath the potti the hull does not have a pronounced V, and it is not yet forward of the leading edge of the keel, but it is SLIGHTLY forward of the deepest portion of the keel and the centerboard. If you go further forward, yes it does get more pronounced. Where my sensors are, they are nearly horzontal (although not as flat as further aft in the same location) and they've never been out of the water on a heel or been in dirty flow. To my knowledge, I've never lost a signal, although I admit that I don't usually spend much time looking at my instruments when I'm at 25 deg of heel. ;^)

Instrument placement is as much an exercise in trade offs as anything else, and your cruising grounds may bear on your decision. It is important to know the trade-offs you make, and to do it with your eyes open. Personally, I still prefer the common location of under the potti. Other locations are quite suitable, and are superior in certain respects (as I noted in my original post).

Oh, Roger... regarding your statement: 'Anyone that thinks such a short distance is going to keep them out of trouble in rapidly shoaling water doesn't know how to properly use a depthsounder.'

I find that statement offensive. If you targeted that to Jim's desire to have his transducer forward of the keel, I find it patronizing and unfriendly at best. If it was in response to my reply on the sailnet list, then I find it insulting. If you read my post you should have noted that I limited that advantage severely. However, I stand by it. If your sensor is in front of your keel, you have SOME chance of detecting an object before you hit it. IF you detect an object, you may not have much time to react, but some time is better than no time. You may even have enough time to brace yourself and keep your face off the deck. If your sensor is behind your keel, you have no chance. Is this proper use of a depth sounder? No. Depthsounders are to get macro (general) depth information and not to detect specific obstructions. Could it be useful information? You betcha. Do I rely on it? No way. Either way, lighten up.

Jim, if you bothered to read this far... consider all of the alternatives and weigh them accordingly. Think about what you need and weigh the alternatives. Choose the one you think will work best for you and you probably won't go wrong. In fact, the biggest limitation has not yet been discussed: Please make sure you have enough clearance ABOVE the transducer (for the sole or other obstructions). It'd really bite to drill the hole only to find that the transducer sticks up a half inch higher than the cabin sole!

Good luck,

Doug
18 Feb 2003


I have a Garmin 240 transom mount fishfinder. The transducer is epoxied in the lazarette, works really well. Still haven't found the perfect mounting location for the display, currenly below the entrance to the cabin on the starboard side...

Gil Eaton
S/V Closing Time
18 Feb 2003

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