C17LT Bulkhead positioning

I was ready to wire in the bulkheads of my C17LT when I discovered a discrepancy in positions between the plans and the instruction book.  The plans have the fore bulkhead at 61 3/8" from the bow while the instruction book mentions 64".  Likewise the Aft bulkhead on the plans is at 121 1/4" vs. 124" in the book.  Furthermore, the deckbeam is 89 1/2" in the plans and 93" in the book.  Intuition tells me I'll be alright as long as I can 1.) leave enough leg room in the cockpit with teh fore bulkhead and 2.) make sure there is enough room between the deckbeam and aft bulkhead for the coaming.

My prime concern is whether those 2 3/4" in positioning the deckbeam and aft bulkhead will affect the trim of the boat in the water once I get my 200 lb future son-in-law aboard? Doesn't sound like much, but I'm not sure how it translates into actual fore/aft balance?

4 replies:

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RE: C17LT Bulkhead positioning

I don't know much about your question, but in my case, sometimes I looked at the wrong plans in the instructions and was temporarily confused about the numbers.  That's probably not your issue, but just throwing that idea out there.

RE: C17LT Bulkhead positioning

Tony --

You've got the right idea; the point is to create a cockpit that fits the largest paddler likely to use the boat, and to position the deck beam so it supports the deck just forward of the cockpit opening.  You want a little extra space behind the rear end of the cockpit so you can attach the back band forward of the aft bulkhead, but you don't need anything more than that.  By the same token, you don't want to unecessarily eat into the spaces available for stowage in the forward and aft compartments.

As far as trim goes, the bulkheads and deckbeam are negligible considerations; they weigh practically nothing compared to your future son in law's 200 lbs!  The more important trim question is where he will sit; you want to make sure the cockpit is correctly located.

A word of warning: test fit the bulkheads first, and look at them critically. The forward bulkhead especially can be too short if cut according to the plans (I know; my LT-17 is plans-built).  You might want to make cardboard mockups of the bulkheads first, and test their fit.  Look not only at their fit thwartships, but also at how they'll fit up to the deck above them.  It's not unusual for there to otherwise be a gap there which you'll need to fill later on with thickened epoxy.

Also, make sure everything is fair.  You probably already know this, but you don't want to distort the boat's lines when you position the deckbeam and bulkheads.

Last but not least, heed Runriverun's advice, and double and triple check every measurement and instruction and think it all through before committing yourself!

RE: C17LT Bulkhead positioning

Thanx for the response.  I built a 16LT a few years ago, but did not have this discrpency as the instruction book refers to the 17 not the 16LT.  I think I'll be okay.  The 16LT turned out terrific!

My reference to trim had more to do with the positioning of the seat within the cockpit and aligning with the coaming.  Moving the aft bulkhead 2" fore or aft would, in turn, have an affect on the positioning of the coaming/cockpit/seat and centr of gravity once the paddler is on board.  It sounds like that 2" is not that material? 

 As for your comment about the fore bulkhead being a little short; I experienced that with the 16LT.  It took a little more expoxy than I would have liked to fill the gap, but it ended up just fine.

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