I have a 1959 Amphibicon in need of a Centerboard Trunk rebuild. I have been pondering this question since I got the boat, but now with the rebuild looming, I am forced to make a decision about it: Do you coat the interior of the CB trunk with bottom paint?
This boat is spending most of her time on a trailer, with most of her sailing in fresh water, but we do have long range plans for a several-weeks' vacation in salt water to the Keys, and I am trying to find a berth were she can stay in the (fresh) water at all times.
The top portion of the trunk is Oak, and does not appear to have been painted on the inside, as far as I can tell. Perhaps this is why all this wood has rotted out? The centerboard itself is Teak, and is in great condition except for a slight warp. This has bottom paint only on the portion that sticks down out of the keel.
Other than a few repairs, almost nothing on this boat is epoxied or glassed. My intention is to keep it that way unless someone offers a compelling reason to change it.
My first batch of questions:
1.) Do I need bottom paint inside the CB trunk? or is it somehow exempt from growing nasties up in there? (it is strangely quite clean in there, though maybe simply from a good cleaning when she was pulled out last?)
2.) If I do need it, what bottom paint is going to work best in there for the longest time? I have good access to all surfaces in there right now, and I really don't want to go to the trouble to open this all up any more often than I need to.
3.) Originally, I think thCB trunk was white oak. Live oak may be more easily found around here than white, and I've heard it is fairly comparable. Any thoughts on one versus the other? What about teak, since it obviously survives so well down there? (Though I suppose a few pieces of 3" x 12" x 8'-0" teak would cost more than my whole boat...)
Secondly, the bottom half of the centerboard trunk is actually a slot in the cast-iron keel weight. It seems to be a recurring headache with this design that the keel weight rusts, and therefore swells against the CB, binding it up. Obviously, much contortion combined with much grinding is in my near future, but what can I do long term? Once I get it operating smoothly, I want it to stay that way as long as I can. So far, most people I have talked to have told me not to worry about cleaning up the keel weight any more than necessary, as no one sees it when it's in the water. I've got plenty of rust right now blistering the current paint, however.
Therefore, my second batch of questions:
1.) How much do I need to protect that cast iron? Will it rust away over time? Especially in salt water? Or will it be ok because it does not have access to air under water. (There will never be anything so vulgar as shore power on (or, for the most part, near) this boat, so galvanic action should not be too extreme).
2.) If I do need to be concerned with this rust, do I have to remove it all, or is there an encapsulation product that actually works? (I have used many automotive "rust-encapsulating" paints that were brought to their knees by a single Michigan winter.)
Lastly, what bottom paint(s) would you recommend for this boat for a Central Florida climate? As I mentioned she'll see a lot of trailer time, she'll get a permanent fresh-water berth if I can find one, but she'll also spend periods of up to two weeks in salt. The keel & deadwood are oak, CB is teak, hull is cedar, rudder is glassed/epoxied, the keel weight is rusty cast iron, and a lot of these features are going to have to be completely stripped and started fresh, if it makes a difference.
I've got fresh Brightsides up top, and I am eyeing up Petit's Easypoxy for the hull above the water line, since they have the perfect shade of maroon, if THAT matters. The bottom paint will need to be black or at least black-ish.
Thank you for sharing your thoughts and opinions on these matters with me... I knew I was getting in over my head with this glorious old girl, but why do something worthwhile only half way?