Fast Launch 26 questions for Jacques

[Fuzz]

The designer can set the displacement where he likes, this is not a hard number.
The PPI at DWL for this boat is 320lbs. So for every 320lbs above 3000 lbs the boat will sit one inch lower in the water. The displacement needs to be set at some number in order to give other information like draft, speed/hp needs and scupper locations. None of this is a hard number but it gives a builder something to go by. Hope this helps.

[Matt Gent]

Right. The "DWL" part is drawn water line. So he assumes you have 1200lb of people & stuff and draws the waterline there. Boat will be fine with more people & stuff, it will just sit lower and go a little slower or burn more fuel than the projected performance.

Depending on what I am doing, my boat is loaded to under 4000lb or approaching 5000lb. You can feel the difference but it is safe and functional over a large range.

[Raky0311]

thanks Matt and thanks Fuzz,I can see now why the designer insist in keeping this boat light in weight, I think i can build light even if I want to add some features , would be interesting to know the weights reference that Jacques use to calculate the 1800 lbs. of empty boat, like engine weight, fuel tank weight (metal or plastic), was the toilet weight considered?, the study plans show a drawing with what appear to be a winlass,was that weight considered, how about the anchor weight?, Just in these parts can be a 400 lbs. of difference, what I try to do is build a boat under designer specifications to obtain the performance projected.
English is not my first language ,so please excuse my poor redaction

[Matt Gent]

No worries on language; we understand, and boat building is a global affliction.

You can build a bill-of-materials spreadsheet to keep track of what you plan. In general most boats built here end up heavier than specified, as we are generally amateur laminators and everyone adds features. An easy place to cut out some weight is to make the flat parts from foam or honeycomb - the pre-skinned Nidacore or similar panels have incredible stiffness at low weight.

However in my experience the biggest factor will be the stuff and people you bring on a given trip. As long as you keep within what is safe for the design, and adjust your expectations to the particular trip, all will be well. I wouldn't stress over a hundred pounds in the build, you won't notice the difference on a boat this size.

[Raky0311]

thanks Matt, yes I probably overthinking this too much, that's how my brain work ,thanks.