Motor mount super ply

[kenjamin]

Having invested a sizable fortune in 7-ply sapelle for the bottom planks of my Caledonia Yawl, I look at the numberous scrap pieces of it laying around the garage and I see money. Recently I took a plywood inventory of what I had left for the rear seat and motor mount and I seemed to be coming up a little short on the thick stuff for a really strong motor well box. Then it dawned on me that the scraps could have bevels put on their long edges and they could be spliced together and sandwiched between two 3/8" thicknesses to become the core of 1 & 1/8" super plywood or sandwiched between 1/4" ply for a 7/8" ply. And of course 1/4" scrap core with 1/4" sandwich would yield 3/4". My plug-in circular saw still has the West System Scraffer attached so bevels are very quick. If you don't have a way of doing quick bevels I suspect for this application a 45° bevel with a circular saw would work just fine also. I plan on gluing the splices and the sandwich all at once so the core will stay nice and flat. What do you guys do with all your expensive scraps?

[paladin]

Precisely what you are contemplating. I built the rudder and centerboard and numerous other parts of a Searunner 31 using that technique with Schindler's T-88 epoxy......and after several years and until the day I sold it...nothing broke....and I did 3/4 ths of a circumnavigation in it.....across the Indian Ocean and all over the South Pacific...

[Dave Wright]

Store them all over the place for years. Trip over them. Look for a perfect piece for some odd job and scatter them all over. Trip over them some more. Reorganize them and store them somewhere else. Repeat multiple times. Then really enjoy them by burning them in the fireplace on a cold day and relaxing in the glow.

Dave Wright

[kenjamin]

I'm building a motor well box for a caledonia yawl. The design of it is such that if you hit something hard enough with the motor while it is in use in the well, it could tear out part of the bottom of the boat. It needs to be good and strong so that doesn't happen. Also the motor needs a good thickness to clamp to so it doesn't rip out at the clamps while it's running. Of the two, I think I'd rather have it break above the waterline than below. Dave, I hope your fireplace has a good draft as burning glue is not something you want to be breathing, but I hear what you're saying. I'm building a 19'6" Caledonia Yawl in a 21' deep garage – actually had to poke a hole in the back wall to make room for the tip of the bow. My wife was not too happy about it. Space – the final frontier.

[Kaa]

I'm building a motor well box for a caledonia yawl. The design of it is such that if you hit something hard enough with the motor while it is in use in the well, it could tear out part of the bottom of the boat. It needs to be good and strong so that doesn't happen.

That actually argues for making the parts of the hull around the motor well good and strong, as well as the joint itself. A good engineering approach is to consider what will break first and make sure that it's not the worst-case scenario. If you hit something with enough force that things will break, what would you prefer to break? My guess is that top of the motor well breaking off is much better than having the entire indestructible motor well being torn out of the hull.

Kaa

[kenjamin]

If the motor well were oversized a bit, the wood that the motor clamps to could be designed to be replaceable. That way if the lower unit hits something hard enough, the motor's clamps would break the replaceable wood piece and the entire motor would drop through the hole in the boat's bottom thereby pulling the key out of the ignition and shuting off the motor. It would be also helpful if the motor well were sized large enough so that it could break loose but small enough to catch the head of the motor so that the still spinning propeller would not be able to swing up and tear into the bottom of the boat. If the motor well were oversized a bit there would be more area around the hole in the bottom that could get torn up and abused by an accident before any bad would come to the actual sides of the motor well. There could be slots on side walls of the motor well that could be made stronger than the motor mount wood that they are holding in position for the motor to be clamped to. That might actually work. What do you think?

[boylesboats]

If the motor well were oversized a bit, the wood that the motor clamps to could be designed to be replaceable. That way if the lower unit hits something hard enough, the motor's clamps would break the replaceable wood piece and the entire motor would drop through the hole in the boat's bottom thereby pulling the key out of the ignition and shuting off the motor. It would be also helpful if the motor well were sized large enough so that it could break loose but small enough to catch the head of the motor so that the still spinning propeller would not be able to swing up and tear into the bottom of the boat. If the motor well were oversized a bit there would be more area around the hole in the bottom that could get torn up and abused by an accident before any bad would come to the actual sides of the motor well. There could be slots on side walls of the motor well that could be made stronger than the motor mount wood that they are holding in position for the motor to be clamped to. That might actually work. What do you think?

Very good idea.:) ... It does makes sense... I'll remember this for the next boats...

[P.L.Lenihan]

Scraps,cut-offs and other odd bits not already destined for a particular part or service go straight to the trash otherwise I would be forever wasting time attempting to figure out what useful small bit of something it could be used for. Besides, this way, I avoid lots of useless clutter in an already too cluttered bowshed.
Your proposed use appears workable,especially as you are that point where you need to make something smallish anyway.Go for it.

Peter

[paladin]

depends on the size of the boat but you can make some nice sheaves and blocks with the wood....