Questions on a Displacement Hull

yeah, but a 1/3 of those are only 6mm ply

The whole thing only weighs 1,100 lbs - 500 kilos, of which 50 kilos is goo.

Thats pretty efficient.

and if someone has to get back to land quickly, it will do 25 mph with the bigger motor.

 

hershey2014, the original poster, wants a boat with a pointed bow built of aluminum.

 

Agreed about the content of the BOM, but it's still a lot of sheets to cart home from a supplier.

I still think a 20' or 22' boat, (with a sharp end) will accommodate the volume desired.

 

Loading & Unloading

Does the lake have lots of good docks ?

I'm thinking you want reasonably high bulwarks with seniors involved, but the flip side is they will not be comfortable climbing over them to enter or exit.

If docks are plentiful, you need side access flush with the deck.

If not you may need more like a bow ramp - landing craft style - suitable for beaching.
Though this doesn't fit with the bow design already mentioned, a landing craft design will give you the width given your requirement for wide stance in a short length, and there are many designs already available in Ally. I guess this is at the function end of the form vs function scale.

 

Steps up the side of the cockpit, usually near or part of a seat, aren't difficult to build and can solve debarking issues.

 

yes, but

For an 18ft boat, with the characteristics of aluminium , costly to engineer, and complicated to build.

I reckon Plywood would make a good solution.