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Bottom Help

Posted by Peter 
Bottom Help
February 29, 2020 02:39AM
Ok. So I think I've found the leak issue. It seems it's where the bottom plywood was seamed, it has been leaking for a while. It is directly under the rowers seat/hatch. The bottom is 1/2 inch ply. The leak has caused the ply to get punky 2 to 3 layers deep. Mainly on the starboard side.

I've attached some pics. My thought was that I'll need to slice about a 1 foot section out of the bottom ply. Hatch edge to hatch edge, and re-splice it with a new piece for starters. As I've said I plan to fiberglass the bottom with the restoration. Does this initially sound like a plan? That punky ply is not very stable and will only get worse. Either side of the hatch/seat is solid.

Need some advice, being a novice on bottom work. Thanks in advance!!!!

Re: Bottom Help
February 29, 2020 01:29PM
What boat is this? How old? It looks like a framed boat with ribs.

Glassing the outside will likely fix it. For a while anyway.

Boat restoration is a lot of work. Some of us were born with a genetic defect--and we like to do this work. But not everybody is so afflicted.

The inside of that rower's seat box shows what looks like flaking/peeling epoxy resin that was applied WITHOUT glass fabric. That's always a mistake. Epoxy resin is for laminating woven fabrics, usually but not always fiberglass fabric. Epoxy by itself just peels off like expensive paint. I'd scrape that peeling resin off and maybe glass the inside bottom of that box too, because it's on top of an aging plywood scarf in the bottom panel.

Primarily prep and glass the outside, which sounds like your plan. You might want to consider removing the outside "chine strip" and glassing over that, so the bottom fiberglass wraps over the outside chine and up the side of the boat a few inches.
Re: Bottom Help
February 29, 2020 05:23PM
Hey Sandy! This is Peter. You and others have already been extremely helpful in my previous posting, drift boat restoration (new member). Thank you!!

And thank you for this advice as well! The boat was built in the 80s and it is a framed boat with ribs. Attached a pic for a better view. Still trying to figure out what plans were used for the build. I suspect I may have that genetic defect as well, based on the fun I'm having...

This sounds like a good plan! You are correct, it definitely has that flaking peeling surface. So, I'll remove all that and get the wood as clean as possible, then glass the floor inside the hatch. The weather here prevented doing the bottom first, so I've been stripping the interior.

I'm pretty sure the varnish has not been stripped down to wood since it was built, patched yes.

Thank you again for your help! It is much appreciated!!!

Re: Bottom Help
February 29, 2020 06:02PM
Lookin good Peter
Re: Bottom Help
March 01, 2020 02:28PM
RE> removing the outside chine

Most framed boats have a chine strip screwed on over top of the joint between angled side panel and flat bottom (flat side to side anyway).

What is the purpose? It's not clear. It covers a traditionally leaky joint, offering a way to keep a thick bead of caulk in place underneath. The chine takes the most damage too, so the chine strip takes the bulk of the hits, and can be periodically replaced.

So far so good. But the chine strip causes annoying "chine dip." Chine dip is what happens to the boat when you get it suddenly sideways to a fast current. The friction of the chine strip causes the boat to dip down on the upstream side. This is annoying at least and dangerous at worst. It also makes the boat slower to turn--at all times.

Boats with a widely rounded chine (like many molded glass boats) sometimes go too far and become squirrelly. They don't track well (maintain a direction). The best compromise in my irrefutable opinion (just kidding) is no chine strip with a small radius round-over at the chine corner. Make the chine corner as sharp as you can while still being able to wrap glass without forming bubbles. Roughly the equivalent of a 1/4" inch round-over bit on a router.
Re: Bottom Help
March 02, 2020 12:36AM
Thank you sir! My heat gun and I have developed a close relationship! :-)

Thank you for this great info! You anticipated a couple of my questions. My boat currently has a plastic 1 1/2 " strip along the edge which has badly deteriorated. (See pic) My feeling was to lose it completely and run the fiberglass up over the edge. I believe you confirmed that. My other concern was the sharp edge created, you also answered that by creating that quarter round to shape and ease that issue.

This has definitely been a learning curve! As long as I've worked with wood, this is a new experience that I am absolutely relishing! Terminology has been one, but your explanation of the chine was great!!

One of the things I've enjoyed most is the process, it never gets old. Something new everyday! I tend to be a planner, I like the think several steps ahead to ponder it and make thinking adjustments prior to starting. Though I'm a few weeks out from the bottom work, based on the temperature/weather stabilizing. Knowing this new info allows me to plan!

Again your assistance is invaluable!

Re: Bottom Help
March 02, 2020 12:49AM
Those old chine strips--whether metal or wood--got installed with screws, which make moisture highways into the underlying wooden hull.

It's best to get rid of it and glass over instead, to maybe 2" inches past the chine. Your photos have zapped my lack of certainty. Chine strips are not good.
Re: Bottom Help
March 02, 2020 04:00AM
Cut it out and patch it in. Remember to follow the rocker curve. Not very likely going be pretty or easy unless you’re really skillful. Go slow.
Re: Bottom Help
March 02, 2020 04:37PM
Will do! Thanks!
Re: Bottom Help
March 07, 2020 04:26PM
Sorry about not responding earlier but life has been busy. Unfortunately, plywood's alternating layers provide pathways for the movement of moisture and consequently also allows any microscopic organisms to travel too. While it appears that the damage is localized that may not be true, it may be several inches of several feet from its initial appearance. Therefore the plywood may eventually fail in a distant location. To reduce the opportunity for failure scarfing in new plywood is the cure. Removal of all plywood with discoloration of the inner layers and a few centimeters beyond is recommended. A scarf half the depth of the thickness of the remaining plywood cut with a router bit will provide a surface on each piece of plywood to glue it in. Laminating fiberglass cloth with epoxy on the inside and outside surfaces will provide additional protection.

For further details and pictures of this process visit www.woodenboatpeople.com and use the search function to look for AJ DeRosa and check out his repair posts. He shows the entire procedure and explains it quite well. These were published in 2011 or so.

Rick Newman
Re: Bottom Help
March 08, 2020 12:22AM
Thanks Rick!! This is really good info. I'll definitely check it out! All help/knowledge Is appreciated. Never done a bottom before, but looking forward to a new challenge! Thanks again!
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