[Rhodes22-list] Hull thickness and keel ballast

[The Rhodes 22 Email List]

I am thinking that it might be of interest to some of the Rhodes owners if I
document my work and ideas as I continue with the restoration of Ariel. 

Having removed all of the thru hull fittings on my boat and also having
removed the bottom paint I have a couple of observation that those with
older boats might find useful. Mine is a 1976.

Hull thickness at about 12" from the centreline is about 3/16th" thick -
including the gel coat. I have no idea what thickness is ideal but this
"looks" a bit on the thin side to me. 

Where the hull rested on the forward end of the trailer bunk on the
starboard side I noticed that the hull had deformed quite noticeably. A few
years back I raised the boat on the trailer to take the pressure off at that
point and slowly the hull returned most of the way, but not entirely, to its
original position. This raised the question in my mind as to the thickness
of the board located under the keel on the RC trailers. In my case the
original board is missing and replaced with a 1.5" thick board. If anyone
can confirm the thickness of the original board I would appreciate knowing
what it is. Otherwise I think I will double the board thickness to 3".

On inspecting the hull with the bottom paint removed I noticed an array of
hairline cracks in the gelcoat where the deformation occurred. The
deformation tends to confirm for me that the scantlings were a bit on the
light side and this seems to be further confirmed by the General Boats
website where Stan reports that this trailer deformation was a problem with
earlier boats and as a result later boats were built with thicker hulls. It
would be nice to know how much thicker they actually are. So I think that I
will try to stiffen the boat below the waterline by adding a couple of
layers of cloth on the inside of the hull between the V birth and the
cockpit where I have access. I have removed all structures from the inside
of the boat including the stringers for the floorboards so access is not a
problem in the main cabin area.  In this case I think it might be better to
use polyester rather than epoxy. The only reason I say this is because I
read in an article on osmosis repair that if a boat has water pooling in the
bilge on a constant basis that one can coat the inside of the hull with
epoxy but the article stressed, without explanation, to only coat the area
where the water stands. I wonder whether the low porosity of epoxy might be
inclined to trap moisture in the hull thereby promoting more osmosis.

I have examined the keel sections more carefully including the drilling of a
number of holes that allow me to judge to some degree the content of the
keel and the feasibility of removing and replacing the ballast material. The
material is a mix of lead flakes and some kind of material that is crumbly
and soft. There are many large voids in the keel that can be determined by
tapping and I confirmed by drilling holes. 

My examination and more careful measuring suggests that gaining sufficient
access to the keel areas from inside the boat to be able to remove the
existing ballast and repair the keel cracks from the inside is not feasible.
The width of the cavity appears to range from less than 4" at the centre to
less than 2" at the ends. Therefore, my plan at this point is to repair the
keel by adding at least two layers of cloth and epoxy on the outside and
around the bottom and up at least 4" into the slot. The skin at the centre
of the keel is very thin and appears to be less than 1/8" so strengthening
the keel would not appear to be without merit given the serious cracks that
have formed at the bottom of the keel. 

To address the ballast problem I plan to drill a number of 1.25" holes
through the sole into the cavity. I will then try to tamp down what loose
material is there by using a rod. I will then add small lead tire balancing
weights as best I can and then pour in polyester resin to fill voids and
hold the mix in place. I am thinking polyester because it is less than half
the cost of epoxy and I believe I can slow down the cure rate and heat by
using the minimum amount of hardener - although at this point I have no idea
what that minimum would be. I could also control heat be doing the pour in
stages.

I have confirmed that the ballast that is glassed to the floor of the hull
just in front of the mast post is steel bars and based on the dimensions has
a volume of .33 cu. Ft. making the weight about 160 lbs. If I am unable to
get sufficient weight into the keel I might add additional bars of lead
along either side of the centreboard. The problem is that I have no idea
what the weight is of the ballast currently remaining in the keel. The boat
seemed to me to be very tender and I have always thought that some
additional ballast would be helpful so I expect that if I go at this with
some caution it should work. If possible I would like to launch the boat
after the ballast is added but before it is bonded in place to see how it
sits in the water and handles. That said, I would prefer to complete the
interior before reinstalling all of the running and standing hardware and
stays but perhaps I should rethink that approach. I worry that if I launch
the boat before I complete the interior, I might never get it done.

As usual, I value any suggestions, cautions etc.

Graham 
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