Eastport Pram - bulkhead "tabs" and mortises

The plans for the EPP had me cut the bulkheads and the daggerboard trunk pieces with "tabs"–little jut out's that look like they're supposed to fit into a hole.

The plans also showed little boxes annotated with "MARK OR MORTISE FOR BULKHEAD", for these tabs to fit in I think.

My question is, Are these necessary? I have seen a few builds of the EPP and it does not look like any of them had these tabs or slots for them.

So, trying to figure out what these are for. Can I snip these tabs off?

4 replies:

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RE: Eastport Pram - bulkhead "tabs" and mortises

   A follow up would be, should these be more like grooves cut into the bottom panel or hole all the way through that the tabs sit in?

RE: Eastport Pram - bulkhead "tabs" and mortises

The tabs and mortises are there to provide alignment and temporary support. They make sure that the components go into the correct place in the boat and then hold the pieces together while the fillets cure without needing clamps, screws, etc. The tabs disappear into the mortises and are covered up by the fillets so they would not necessarily be visible, though the ones for the bulkhead should be visible from the outside.

As the last picture shows, the holes go all the way through the bottom.

You can certainly build the boat without the tabs but you'll need an alternative way to make sure that everything is properly aligned and stays that way while the fillets cure. Other than providing a tiny increase in the gluing surface the tabs don't really affect structural strength.




RE: Eastport Pram - bulkhead "tabs" and mortises

Laszlo's correct.

Your latest post answers my question in my reply to your initial post from a day earlier.

I'd assumed you were working from plans as the CLC-provided kits come with those tabs and mortices pre-cut.

Never having done a boat build from CLC's plans myself I couldn't say that their plans may not make it clear that these elements are to be part of the 'getting out' process when making useful boat parts out of sheets of flat plywood.

Indeed they're there for a reason, to aid in assembly, simply an artifact of the CNC process CLC's developed for kit production. Their inclusion may confuse first-time plans users in that theyr'e not really necessary for a proper build and they may complicate the "getting out" part of parts-cutting, but in the end they're useful things when it comes time to put pieces in their proper places for a boat.

RE: Eastport Pram - bulkhead "tabs" and mortises

Thanks Lazlo. I must say, you're basically walking me through my build at this point and it is much appreciated!

And yes Spclark, it's the situation we talked about in that post–find the mortises for the trunk, base the middle frame location off how the trunk sits therein.

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