EcoSmart, an efficient motorboat

Two boats of equal displacement and length, but of different widths, will have different depths in the water. Per unit of immersion, the wider vessel will have greater load capacity. No calculations necessary.

I am not an NA. I'm an artist with some experience around boats and a tiny amount of boat design knowledge. I don't ask these questions to argue or even correct, but to encourage expanded thinking. I could be wrong and it's okay with me if I am. I just don't think I am.

If you are keeping the displacement the same and the length the same and the load capacity the same, the wider boat will be shallower in the water because the overall volume of displacement is equal between the two vessels. So, one variable has to change. It will be the draft. A shallower draft will plane more easily than a deeper draft.

A wider boat of equal length is simply a bigger boat in the water unless you reduce the freeboard and or cabin capacity vertically. This means the weight of both boats are close to each other and I would think, in terms of energy spent to get efficiently planing, less energy would be needed for the wider boat.

Again, I'm willing to be wrong. I just want to see where these ideas have been addressed.

I like your concepts, I love your goals, I hope you are very successful.

-Will

 

You do compare two boats with different load capacity and interior space. What you are doing is a completely different topic than what is being discussed here. Your wider boat will also pound harder and have greater resistance in oncoming waves.
Here I discuss normal planing boat with the same total weight, load capacity and interior space.

 

So sorry.

-Will

 

Would it be cheating to fill a lifting volume with helium (or hydrogen, but keep it far away from me), to reduce effective weight?

Or to vent heat into the interior, to give it a bit of hot air lift?

 

I see lots of hot air being vented at times, never really seems to lift efficiency though
Jeff.

 

EcoSmart 100
10,0/9,4 x 2,5/2,1

Here shows an ongoing project that is an application of the principles presented earlier.
This boat is primarily optimized for semi-planing speed. By using the technology with the aftship interceptor, the boat can also be suitable for planing speeds.
JS

 

My experience in boats this size suggests that the normal rules and proportions start to fall apart under about 2 tons. Boats with very shallow drafts just don't perform as well as you would expect, and opting for a narrower hull and deeper draft will improve performance. On small boats, windage, yaw stability issues, whisker drag, seaway drag and other effects are relatively larger than than on bigger boats. Getting the prop 2 inches deeper can help a lot. The fatter boat may transition to plane at 9 knots instead of 9.5, but does anyone care? Outside of that half-knot range, the skinnier boat will be handier. The trick here is to manage the angle of the bottom when at low planing speeds. It you can get the boat to run at a decently low trim, using any tricks you can muster (like interceptors) then all is good.

It might be interesting to express interceptor effectiveness in terms of equivalent beam. Set the planing trim angle as the common constraint and find the beams of the boats with and without interceptors.

 

philSweet
Please show us your numbers, no guesses.
Compare boats with the same total weight, load capacity and interior space
JS

 

I’m interested in a hull like the EcoSmart 100 as a cruising boat for a couple. Mid 30s ft long, semi-planing with two small outboards. Bonus if it fits in a 40’ container.

What are your thoughts on the initial stability of the 6 panel trapezoid bottom at anchor or lower speeds? Looks like it would be tender in roll.

 

Matt Gent
Reducing the width so that the 10 meter boat goes into a container reduces the payload by about 500 kilos.
To increase the roll stability, the bottom panel can protrude slightly transverse. The midship interceptor in the waterline panel contribute to roll stability during speed.

 

Today's test with EcoSmart 83 with electric powertrain.

 

During the summer, the EcoSmart 83 was supplemented with a larger foredeck and an aft deck. In addition, the tilt of the engine has been adjusted and the propeller replaced. This has led to a significant improvement in performance. See attached diagram.

 

What is that assumption based on? Displacement hulls at low speeds require less power and are more efficient in MPG.

 

Fitting in a 40’ container invites all sorts of shenanigans- but weighing the same? Displacing the same? Same accommodations? Demountable? Smaller of course…

 

And on this very site!

https://www.boatdesign.net/threads/trimaran-motorboat-stabilized-monohull.29665/page-7