fallguy1000 wrote: ↑Wed Dec 22, 2021 4:42 pm
dennisb wrote: ↑Wed Dec 22, 2021 11:51 am
If I take the DWL weight for the 25' version, 2800 Lbs and multiply it by 1.331 I get a 3727 Lbs for a new DWL weight, the boat should have the same draft (scaled). Is this logic correct?
No. The larger version boat will have 121% the wetted surface area (roughly). And thanks to Phil for correcting me.
If you add 133% of the weight to 121% of the area; she's gonna be lower in the water. This is one of the reasons I am not a fan of scaling in all directions.
See what the other guys say. I am an amateur here.
Dan,
It isn't 133% of the weight to 121% of the area, it is 133% of the weight to 133% of the volume below the Designed water line. So it should work out just fine. And yes, if the original draft was 10" the new DWL would be at 11".
My $.02 on this matter is to not worry too much about it. Build the boat efficiently and have a plan to add ballast as needed if necessary. I think it will all work out okay. The weight of the boat should grow 21% just with the extra material not including any extra layers of glass.
I will say that a 90-115hp OB seems a little small for a 27.5' boat even one with only 6* deadrise. I think the extra 100lbs for a 150hp would be well worth it and probably wouldn't affect fuel economy much. I'd rather not be running full throttle just to get to cruising speed.
Phil
Edit: I would be curious what Jacques' input would be on this.