Reverse Bows

orion · 02-04-2007, 04:21 AM

Reverse bows, is it a new trend in yacht design?
Like this Gatsby styled laid back cruiser...
Opinions?

Eric Sponberg · 02-04-2007, 10:07 AM

Personally, I think the stylists are overtaking design to the detriment of good naval architecture. Hydrodynamically, the reverse bow does not make any sense at all. The shape and volume of the hull goes against sound seaworthiness in a seaway--as such a boat powers through waves there is little reserve buoyancy to keep the bow high in relation to the waves and deflect spray. The boat will tend to sumberge in seas, making for a very wet ride indeed. That's fine if that is what you are looking for, and if you are willing to make that sort of compromise towards style.

Eric

KCook · 02-04-2007, 11:36 AM

Could this model be a Med special? Not really intended for big swell?

Eric's points on buoyancy are right on the money, of course. But to some degree couldn't this concern be applied to all of the "wave piercer" family?

Kelly Cook

AMG · 02-04-2007, 11:47 AM

Quote:

Originally Posted by KCook

Could this model be a Med special? Not really intended for big swell?

Never been to the Med Kelly?

KCook · 02-04-2007, 05:06 PM

Ooof! Got me Lars. Only wish I had been to the Med. So is typical Med swell is the same as the Atlantic?

Kelly

AMG · 02-04-2007, 05:30 PM

A little less, but 8-9 meter waves are common in storms and up to 25 m (80 feet) has been measured. I think a large cruise ship was hit by such a wave a couple of years ago and lost all controls when the bridge windows broke...

This was between Corsica and Mallorca, where the Mistral winds can be pretty naughty.

KCook · 02-04-2007, 09:31 PM

Yikes !

Whiteho2 · 02-19-2007, 03:39 PM

This was my Coventry University Final Project. Indeed the initial idea for the reverse bow was a styling element but this 50m yacht was designed to be fast so her bow would raise at speed. The previous thread was correct however in saying that youd be drowned if standing on the forward deck area when in motion.

Innomare · 02-20-2007, 03:35 AM

Quote:

Originally Posted by Eric Sponberg

Personally, I think the stylists are overtaking design to the detriment of good naval architecture. Hydrodynamically, the reverse bow does not make any sense at all. The shape and volume of the hull goes against sound seaworthiness in a seaway--as such a boat powers through waves there is little reserve buoyancy to keep the bow high in relation to the waves and deflect spray. The boat will tend to sumberge in seas, making for a very wet ride indeed. That's fine if that is what you are looking for, and if you are willing to make that sort of compromise towards style.

Eric

Eric, I agree with you on the wavepiercer bow.
However, volume above the waterline does not necessarily equal seakindliness. I recently made a short trip on an Axe-bow ship and saw video footage of tank testing comparing a conventionally bowed ship, an axe bow and a wavepiercer in heavy seas.
The wavepiercer acted as you say, but the axe-bow behaved a lot better at high speeds in heavy seas (and was still going fine when the others were basically sinking). It had a dry ride while it has little or no reserve buoyancy in the bow.
But, there's a lot more to the axe-bow concept than a vertical stemline and high freeboard at the bow. Including some compromises most yacht-owners would not like to make.

Best regards,

Bruno

orion · 05-19-2007, 04:15 AM

Which boat would you be in?
I think the reverse bowed boat have softest and also driest ride.
It also goes at 13 knots vs the traditional flare bow boat goes 8 knots

http://www.youtube.com/watch?v=2aX5Arv-5vw

MikeUSCG · 10-21-2007, 01:10 PM

In my opinion, the style of a reverse bow is worth any mild drawbacks in handling. This is what i drew up this afternoon; forgive my art skills, please.

CODOG · 10-23-2007, 09:12 AM

Give me a good old 45 degree (fwd raking) stem anyday. I'd rake it even more if the interior package vs overall length would let me.
Got bored, so I worked out that for a (powered / planing) hull designed to be largest possible just under the 24m Load Line Length rule, I can have a hull around 27 metres long stem to transom if the stem is raked around 45 degrees. If the stem is vertical, the hull cant be longer than 25m from stem to transom. Around 6 feet less deck length, designed under the same rule.