Tips for repairing mahogany deck
A multitool can’t make a straight enough cut to get a tight fitting patch. Usually for patches I’ll use a router and a template to remove the damage but If that deck is curved you’ll need a different option.
With that amount of damage and all those fasteners (based on the plugs) I’d consider replacing the whole top. There’s also likely more damage than you can see and blending in that many patches won’t look good anyway.
You can still do a router for these curved pieces. Just make your template as a whole rather than pieces individually stuck to the workpiece. Then inlay a slight proud piece and make the curve happen in place with a spokeshave and/or sander
Thank you and I agree. Unfortunately it’s not possible to replace the whole deck this year, although I wish to do it in the future. You don’t think it’s possible to cut with the multitool along a taped aluminium ruler? I agree the router option is not ideal due to varying thickness.
Also edit: The plugs are “fake” because the screws are in the other wood sheet below the mahogany which is glued.
You can but those things wander so over the length of those patches the line won’t be clean. You’d be better off cutting it a bit shy with the multitool and truing it up with a chisel.
Do you have access to a circular or track saw?
I see, and yes I could get a hold of a track saw. Maybe that could make a straighter cut?
wtf is everyone talking about, get some 1” x 1⁄4” furring strips tape am down with double sided tape to make a router jig on the boat then you can accurately size your cut out. do small depth passes with the router till your at the depth you want to achieve. chisel out corners. the patch piece you want to cut larger and use a hand plane to get proper fitment
A track saw would be straight as an arrow. Or I guess, as straight as the track.
Honestly you’d be better off going slow with a wood chisel and replacing that entire strip in between those two darker varnished lines. It’d look more uniform you’d be able to dry out and see how big the effected area is and fix any hidden issues around the damaged sections
I would make a template out of paper/tape, and use a plunge router or normal router or jigsaw to cut it off, not a multitool. Trust.
Jigsaw? No
Could try a quality track saw. Use the planer trick. Put pieces painters tape on both the deck and the underside of the track. Put crazy glue on the tape on the deck and spray the tape on the track with activater amd smooth together.
But like others are saying the whole deck should be replaced. The moisture between the two layers might make more expensive problems down the line than replacing it all now.
Also if it’s ply underneath and true hardwood on top do NOT epoxy anything down. The play really won’t move that much in the sun and humidity but the hardwood will. And if you try to permanently adhere it down you might get really bad buckling or cracking.
What about a tracksaw?
3d scanner -> 3d printed template for router
bambu is about to release a cheaper/ more accessible 3d scanner
Boss, we’ve been doing these kinds of tasks with some straight pieces of wood and a single speed router for 75 years. Technology isn’t the answer for everything.
I’m not sure how to make an arced jig
OP isn’t either, as he said his method wouldn’t work
If technology can enable you to get a job done, that’s a good thing
You’re fine with using an electric router instead of a hand cranked drill, aren’t you?
Furring strips are about 3⁄8 thick and conform to curves with some double sided tape. That’s all that’s needed to guide a router. And actually I’m a luthier so the hand crank drill comes out pretty often.
hobbyist woodworker, not a boat builder here (btw, maybe you should ask at u/boatbuilding anyway!) But if there‘s actual standing water in the cracks and possibly between the two layers of wood, ripping the mahogany off completely would surely be the „proper“ repair. If that is not an option, I would open up all obvious cracks and damaged areas, and then let the thing dry really, really long. I‘m thinking months rather than weeks, because I would be super-scared of trapping moisture in when resealing the deck. I maybe would also get it somewhere warm and dry, but then again that might be something you don‘t do with wooden boats because of material shrinkage - boat building is a bit of a dark art, I think …
I’m not a boatbuilder, but I have a general aversion to wood sheet goods being used outdoors, especially in a horizontal orientation. Delamination seems almost inevitable. But I might be wrong. There’s a guy, Southern craftsman marine who I follow on IG and he glues solid teak directly onto, I think, fiberglass, and then uses some black sealant in the gaps.
You’d be shocked to learn how prolific sheet good use is in wooden boat building
Sure, plywood sailboats were pretty common in the 60s. Marine plywood that is.
Yes I agree I was actually surprised that it was a sheet, which I guess explains the damage. I thought it would be at least 20mm thick. This sheet deck is believed to be a repair from the 90s.
That is the normal way to make a teak deck, although screws are used normally to hold the curve until the adhesive cures. Teak, however, is slightly less expensive than solid gold.
As someone who has done what you’re doing before, I would strongly suggest not repairing that top and waiting until you can replace the whole thing. It will end up taking longer and looking much worse to repair it than to replace it. You’ll have to strip the finish off the entire thing and revarnish everything to make it look somewhat even, and it’ll be almost impossible for you to not sand through the mahogany veneer, let alone how much more rot you’re likely to find under the veneer.
Check my post history for what goes into refinishing a mahogany plywood boat like you have. It is no small feat.
I’ll second this, though I see you already have said you can’t do the whole deck now.
The problem is that you’ve almost certainly not found all the water ingress points, and I say that from past (painful) experience. The water has very likely traveled far from the spots you’ve opened up and if not opened and dried it will rot through the deck underneath that ply. If it gets to the deck-to-hull joint it can lead to structural failure.
One thought is to remove the upper ply, dry things thoroughly, then seal with a couple coats of epoxy. It will look awful but might let you get through another season before tackling the replacement.
Where are you located?I also have a Mahagony Boat and will replace my cabin roof with Marine Plywood an Mahagpny Strips and Epoxy.There is a guy in Hamburg selling Marine Grade Mahagoy Plywood for very cheap do to inheritance.DM me if u need any.
Before you start to repair it - find how the water is getting under the finish and stop it from happening. I really feel this needs someone with boat building experience as there will be “the way” to do it and all the others will fail quickly.
Thank you I agree. I think I can establish that the water has come in through the cracks that have been (that now are chiseled out). I have been in contact with boat builders, but everyone has a different solution so I wanted to get further opinions.
This isn’t really a situation for patching, it’s a situation for replacement. Or, if ugly is an option, for fiberglassing over.
What tools do you have?
I have a Bosch multicutter, also have a router and misc hand saws.
Call a priest
I hate resin as the main showpiece. It has distinct 1980s vibes, to me.. Like it belongs somewhere between a TransAm with a T-top and a mullet. Unfortunately, given the gouges, you may be stuck with it.
I like resin for repairs, hidden ones, but this? You could go old school and do a mahogany veneer. In which case you’d be filling old nail holes and gouges with resin anyway to achieve a smooth surface.
Creative inlay may work, if you could figure out a design to match the desk.
Sad. Who lets a beautiful boat like this get into such state of disrepair?
It’s very sad, that’s why I want to repair it and get a proper replace by a boatbuilder down the line.
not a boat builder, but helped my dad restore a couple in my teens. Your decking is screwed down to marine plywood and the screw holes are plugged.
My advice is for dutchman patches. Use spiral upcut in the router set at the 8mm depth with guides dbl taped on deck to make clean recesses for your patches. Use marine resin epoxy. Shave/sand it all flush and refinish. Filling gaps with resin is ok.
The wetness is a problem. Maybe dry work areas with hair-dryer/heat-gun? — idk
Thank you, this seems like a reasonable approach and what I’ve been recommended. I’ve heat gunned the areas and I will let them dry until march before I make the dutchman repairs. Was my preliminary plan anyway. Just a correction too, it seems the whole mahogany sheet is glued. The screwing is actually in the plywood below, is that a strange setup?
up until the 1980s hundreds of screws were used , application of glue kicked in , in the 90s.
Yes maybe that’s why, this repair is probably from the 90s
Looks more like a replace than a repair.
Circular saw for the cuts, along a straight edge that’s clamped/weighted down. Cut at a 45-angle so that when you put the new piece in place it won’t fall through.
You don’t have to buy a quality saw for this job, though I would just because it’s such a useful tool; whatever Harbor Freight has on sale should work, or a more popular brand if you want to buy into a battery ecosystem. If you don’t think you’d cut lumber/plastic/metal much, there are “sub-compact” circular saws that are one-handed, look closer to a multi-tool, but still cut like a circular saw (straight and angled). Good for drywall, trim, etc.
Put in the same type of wood so that wood movement doesn’t become an issue. If you want it to look not-crap, I would sand the whole thing down, then stain and poly-varnish all of it.
(As an alternative idea, if you prep your replacement wood first, you could trace it on the deck and use your multi-tool to cut the trace. Still will be tricky to epoxy it in place without a miter)
Patience man, patience.
Look into Smith and Co. epoxy materials, especially the penetrating sealer. That’s what I have with good success.
That is not a repair job, that is a replace it job. You just need to take the whole top off and build a new one. I would personally put down marine plywood and then glass it unless you are looking for an authentic restoration which even if you replace as new will require frequent maintenance,
Dry the wood thoroughly before any epoxy. Water in the cracks may have seeped under the sheet, and epoxy over damp wood fails early. A moisture meter helps. Router and template beats a multitool for straight cuts. Not a boatbuilder, so check seam sealing with someone who does marine work.
