Sailboat-shaped Powerboats?

[Mat-C]

I've often wondered why you don't see any powerboats that are shaped more like sailboats.
I'm thinking of powerboats in the semi-planing range and sailboats like open 60's etc, or like this sexy new beast from Wally

I get that the slender fwd sections mean that you lose interior volume, that the buttocks might need to be straightened a little and maybe that the big flat back end could be troublesome in a following sea without that big rudder and keel pointing it in the right direction... but surely these shapes are more easily pushed along than the typical semi-planing hulls...?

[Mr Efficiency]

The force driving the sailboat is well above deck, that of the power craft is underwater, which has a significant effect. Then there is the absence of the keel and sail damping, so the otherwise similar underwater shape will give very different stability characteristics. Next you have to consider that driving head on into waves, which the sailboat never does, could make it a very wet boat. And the list goes on.

[PAR]

What I don't understand is why aircraft are more shaped like cars. They do mostly the same thing, well except for the flying thing and you just don't see it much. Every once and a while a flying car shows up, but never an automotive aircraft. Hummmmmmm . . .

Maybe a locomotive car. Yep and car that can climb up onto empty railroad tracks. No traffic, no missed exits, just enjoying the view in your loco-car. When you get to your destination, just drive off the tracks and park next to the poor unfortunates that have plain old cars.

[BPL]

How about Dashew's FPB http://setsail.com/fpb-64-hull-shape/

[BPL]

Or the Shannon SRD hull http://shannonyachts.com/shannon_srd_technology.html

[Mr Efficiency]

Originally Posted by BPL

How about Dashew's FPB http://setsail.com/fpb-64-hull-shape/

I wonder what the motion would be like in steep beam seas. And ultimate stability in big beam seas.

[Mat-C]

Dashew's boats operate at lower speeds than I was thinking of.
The Shannon is (quite apart from being one of the ugliest boats afloat ) a bit closer I guess, though all those bumps and stuff make it a bit of a hodge-podge of different ideas...

Par.. I assume from your reply that you don't know the answer(s)...

[michael pierzga]

They do ! Check out Nigel Irens "Low Displacement/Length Ratio "designs.

http://www.nigelirens.com/ldl/

[Mr Efficiency]

They do what ? What sailing vessel closely resembles that hull ?

[masalai]

Mine is, but it is a cat (40 ft x 21 ft) and maxes out under power in still water at just above 10 knots but it will surf very nicely, - and happily does 19knots then with no nasty broaching habits... Small beam seas are very uncomfortable if the crests are closer than 19ft - in that case change course a bit, for a more comfortable ride (the glass of beer - or wine - does not spill)... If the sea state does not look nice, hang around in the lee and wait a while... Duh...

Or you can buy a maratimo racing boat (about the same weight and LOA as mine, but about a 12? ft beam and does around 200kmh or more...

I run happily on one engine at 6 knots burning 3 litres/hour (0.8 gal/hour) - fuel load is better than 1200 litres (300+ gal.)... Google "my little piece of peace"... The first entry should get you to my build thread...

[Mat-C]

Originally Posted by michael pierzga

They do ! Check out Nigel Irens "Low Displacement/Length Ratio "designs.

http://www.nigelirens.com/ldl/

I guess they are about as close as I've seen... somewhat deeper in the forefoot and maybe flatter in the aft buttocks, but otherwide pretty close....
I'd love to see a set of lines for one...

[daiquiri]

Mat-C, sailboat hulls are designed and optimized for a navigation at some heel angle. It doesn't make much sense to shape a motor boat for the same condition, doesn't it?
Unless we are talking about a design commissioned by Capt. Schettino for his personal use.

[tom28571]

A Dashew Windhorse anchored in my creek last fall a couple times and I had a good look at it by circling around in a runabout. It is a very purposeful looking craft but not at all handsome in an aesthetic sense. It looks to be very efficient for its size but not in absolute sense since it was still only transporting two people and the fuel per mile per knot per person kind of sucks. That brings up a pet peeve about many "green" vehicles, boats or whatnot, that are very expensive, eat up a lot of resources but are "efficient" on fuel per ton.

Shannon's reverse deadrise boats, patents to the contrary, don't introduce any radical new element of hull design, that I can see, that has not been used before. Schultz's patent is probably on some small element or claim in the design. It is a good idea though for specific speed ranges and I use a similar version of the same basic element of aft bottom design myself.

Sailboats and powerboats have sort of come together in recent years so that some of them are very similar. Dashew's Deerfoots, Windhorse and the new sailing sleds (long and light with fine forward sections and wide flatter aft sections) have many similarities.

[Tad]

I think you have to look at the user profile.....people who have $4 million to spend on a powerboat don't want an ultra light efficient hull.....They want a big (wide & high), fast, noisy, aggressive, statement......Fuel use is a minor detail that has no bearing on the purchase decision....styling, ultimate speed, and interior volume are the drivers.......

People who buy 80' Wally type daysailers are a completely different animal. The boats are used for day racing and partying aboard in harbour. Passages are done by delivery crew. The owner never stays aboard, accommodations are for the occasional afternoon nap. Big powerboat owner's in NA usually run the boat themselves, but they don't go far at all and want to get there right now, so speed is the thing. They stay aboard the boat so interior volume and appointments are critical to the sale.

I'm starting to get inquiries for new build Chinese powerboats that the owner will never sleep aboard and will never leave the dock. They are total marina party barges.

[BPL]

Beauty is in the eye of the beholder.
"a fuel burn of about two miles to the gallon"