Hatch garage joints

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Gunfleet

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My 1960s Nicholson doesn't have a hatch garage. I want to install one, not least to allow my spray hood installation to be less of a bodge. I'm a competent amateur woodworker (Ie can joint a board and cut dovetails) and have sourced some 5/8 inch mahogany (aka the sides of an old wardrobe) which will give me the upstands. It's beautiful stuff. I have some mahogany ply to make the lid. But I'm baffled as to what would be the best joint for the forward end. Blind dovetails would look right, but I wonder if they would be too fragile for such an open position. Does anyone have any advice/experience to share?
 
Through dovetails are stronger and look the part.. There will always be some exposed endgrain and you will become a slave to varnish but with a class boat like that you might already be one!
David "Bud" C MacIntosh has nice illustrations in "How to Build a Wooden Boat". I've done several based on his drawings (Sam Mannings drawings actually, credit where it's due!).
 
This "Until recently Boatbuilding instructor" part of your profile is very reassuring. The wood is fabulous - planes like nothing I've ever handled. So I suppose varnishing... yes. I once had a Kestrel made entirely of mahogany (well, not the frames) and it had always been painted.
 
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Personally I don't think strength is too much of an issue and blind dovetails would be my preference with rounded corners. I would not varnish but use thin clear epoxy.
I also agree that aged mahogany is a very nice wood to work with.
 
Finish with either a conventional varnish and keep on top of it, or use a porous woodstain such as International Woodskin for a durable finish that needs minimal maintenance but still displays the underlying wood. Epoxy is not in my opinion a suitable coating, not least because it does not like UV and a hatch garage is in possibly the worst position on a boat for exposure to UV.
 
Epoxy it if you will but put UV resistant varnish on top or it will yellow in time and eventually flake off. Mahogany will take it better than teak but I've yet to see an epoxy that does not yellow eventually when exposed to sunlight. Mind you there's not been much of that the last few summers!!
I like lapped dovetails too, I just make better through ones!!
 
Thanks for the replies all. I have watched a couple of videos of people rounding off through-dovetails on youtube - I think that's the route for me - looks great. I'll just have to figure out who I know who has a bandsaw - I tend to be a hand tool type. And I think I'll use the Woodskin - I did my washboards with it (or probably its predecessor) a few years ago and they've stayed perfect. I'm not a fan of the epoxy approach. When it goes flakey it's ugly and a ghastly job to get off - it doesn't deteriorate at a regular rate so some bits are falling off while others will resist scrapers for years to come :-(
 
Very many years ago I did mine out of mahogany with through dovetails. I think it looks OK. I'll see if I can find a photo. It will not appeal to purists as they are machine cut dovetails. I rounded off the corners. The top is laminated out of (I think) three sheets of ply epoxied together to create the curve. I coated it in epoxy followed by 2 part poly-U uv screen. I wish I hadn't. I don't like the way epoxy ages and have replaced all the epoxy coatings on my boat with conventional varnish.
 
I need a hatch garage to keep water out of the saloon when going gets rough but was going to build out of grp but got to make a mould either female mould or make a male mould out of ply and timber and then glass over then paint with non slip as need to step on deck head for sail stowing so needs to be strong enough.Also needs to look ok as rest of boat showing its age .Regarding OP question if coating with epoxy finish with coats of 2 pack paint should give 5 yr + life.
 
Update. I hadn’t counted on the mahogany being crumbly. It planes and saws but don’t cut easily with a chisel. ��It’s like trying to cut dovetails in Stilton.
 
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Comb joint it & cut the combs on a circular saw or with a wide slitting saw blade in a router if you have one. Keep the fingers about 5-6mm wide & cut them with several passes of the blade so you do not have to cut the end grain with a chisel. If the combs are small they look neater.
Obviously the best way is with a spindle moulder & a bank of slitting saw blades but you need someone who has one.
 
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Daydream believer said:
Comb joint it & cut the combs on a circular saw or with a wide slitting saw blade in a router if you have one. Keep the fingers about 5-6mm wide & cut them with several passes of the blade so you do not have to cut the end grain with a chisel. If the combs are small they look neater.
Obviously the best way is with a spindle moulder & a bank of slitting saw blades but you need someone who has one.
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all good ideas but I don’t have a table saw - no space in my shed. I cut everything with handsaws. I can get quite long rip cuts right nowadays, though I’ve had plenty of practice getting them wrong. I do have a router but again no table. I think in this case I am going to have to bear the ignominy of a biscuit jointer and resorcinol. Or accept defeat and cut up some iroko.
 
Gunfleet said:
My 1960s Nicholson doesn't have a hatch garage. I want to install one, not least to allow my spray hood installation to be less of a bodge. I'm a competent amateur woodworker (Ie can joint a board and cut dovetails) and have sourced some 5/8 inch mahogany (aka the sides of an old wardrobe) which will give me the upstands. It's beautiful stuff. I have some mahogany ply to make the lid. But I'm baffled as to what would be the best joint for the forward end. Blind dovetails would look right, but I wonder if they would be too fragile for such an open position. Does anyone have any advice/experience to share?
Click to expand...

In Portuguese traditional wooden boat building, only through dove tails are used for resistance to humidity. When both pieces have the grain aligned correctly, then both pieces experience the same expansion or shrinkage at the same time and to the same degree. Otherwise, one piece may crack or the joint might loosen. But it has been “some” years since I last made one. Blind were off course never used and half blind even less because you would be exposing the grain of only one side to moisture.

But this is bearing in mind that the wood would not be protected with the modern materials that exist today that may render this concept obsolete and you may very well do a half blind joint if you seal it well, without the danger of moisture creep.
In those days the boats would be beached periodically and then flooded to keep wood moist.

My 2 cents. It has been 30 years since I helped my grandpa build a wooden boat.
 
Gunfleet said:
all good ideas but I don’t have a table saw - no space in my shed. I cut everything with handsaws. I can get quite long rip cuts right nowadays, though I’ve had plenty of practice getting them wrong. I do have a router but again no table. I think in this case I am going to have to bear the ignominy of a biscuit jointer and resorcinol. Or accept defeat and cut up some iroko.
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You dont actually need a table if you have a router, but you would need to use a dove jig. https://www.screwfix.com/p/12-dovetail-jig/17062?tc=FT8&ds_kid=92700022888050361&ds_rl=1249796&ds_rl=1245250&ds_rl=1249481&gclid=EAIaIQobChMI6dfrqZjK2gIVj5kbCh0xWwwREAQYASABEgI9ZPD_BwE&gclsrc=aw.ds&dclid=CIChka-YytoCFTET0wodLuANOg

I don't know the size you need, but instead of going for a larger and more expensive one there are some that can be used to do small portions at a time.
 
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