Breakthru Hull Design...

Feadship X-stream model with Axe-bow:

http://sports.webshots.com/photo/2136713690040129753RQfCgY
http://sports.webshots.com/photo/2019334700040129753yLYrst
http://sports.webshots.com/photo/2901765310040129753JfhtTc
http://sports.webshots.com/photo/2708289580040129753hHkqGh

http://www.***********/news.php?id=68

Axe bow concept:
http://www.maritiemetechniek.nl/downloads/Bijlboeg Gelling.pdf

Nice!

Im specially impressed with the pdf-seminar

Anybody ever hear of "bow steer"?

Kelly

Is that an out-of-shape bow ornament?

You've raised a good point Kelly. A point worthy of discussion. Any takers?

Gosh, I thought 'bow-steer' was when they put the steering wheel all the way up on the pointy end.
No?
Dang!

Then it must be what lots of '70s-'80s Hatteras convertible owners experienced when a Bertram, for example, ran past them.
The deep forefoot of Jack Hargraves' hull design would dig in to wave action that wasn't perpendicular to the Hat's direction, and you'd see those skippers sawing at the wheel to keep the boat running straight.
The modern Hat design (see the YF Hatteras 77 Convertible review) has a shallower entry which precludes that type of handling.

Did I win a toaster?

"It became clear during the first sea trial that the axe bow vessel performed exceptionally well. "It's a strange experience. You see a huge wave coming at you, but the bow just gradually rises, without extreme up and down accelerations." The vessels also proved to be easy to steer. Experts had initially feared that the axe bow might negatively affect the vessel's manoeuvrability and the ability to steer a fixed course. "But the captain complimented us on the vessel's ability to be tightly steered at all speeds."

Regarding the above quote from Redman's post #46, I just don't see it, but then I'm drawing on personal experience. I'm not refering to straight-on waves or stern-quartering waves, or steering straight in calm water, but rather the real-world phenomenon of quartering bow waves, to wit: in the early eighties during the so-called 'Bimini Start' of a particular Bertram-Hatteras Shootout, it was pointed out to me that the boats in the mid-pack, caught up in the wakes of the lead boats, behaved in two different manners. The Bertrams, with their cut-away forefoots, ran straight through the slops. The Hatterasses (Hatterai?) were noticeably "bow-steering" with their helmsmen sawing at their collective wheels trying to run in a straight line.
I have run some of those older Brand H boats and have felt how the bow can get pushed around by wave bullies esp. in confused seas.
I am not picking on Hatteras. Jack Hargrave chose a deep forefoot plus a deep keel aft to maintain proper dynamics.
It's why an arrow has the fletch (the feathers) on the back end: the center of drag better be aft of the center of effort, or it's 'fanny over teacups'...with exceptions like the Grumman X-29 forward-swept wing aircraft requiring a computer making forty-some odd corrections per second to keep it in the air.
But I digress.
I admittedly did not read all the posts in this thread. Are there axe-bow boats running around at higher-than-displacement speeds that the knowledgeable captains on this Forum would not term as "squirrelly"?

Concept understood.
But, the vessel in post #47 appears decidedly un-trawler-like. And with a slightly smaller crew manifest than those depicted in #49, I might add.

Just a thought, but Huckins has had nearly plumb stems for years, coupled with a deep forefoot and semi-concave forward sections much like these "revolutionary" axe bows... Foresight, coincidence, or just late to the party?

Efficient and seaworthy?

Half the horsepower, twice the range and sea kindly! Compared to what? Most production boats put issues like efficiency a long second to accommodations and fit out.....

In the days when efficiency and seaworthiness were primary design objectives we saw boats up to 50’ frequently cruising at 10-15 knots for fuel consumptions of better that 2 nmg (< 1.5 litres per nm). Today we have towering barge arsed tanks that guzzle fuel at much higher rates being flogged by spin merchants to the boating public.

What about a return to the old Midnight Lace 44 that used around 40 litres at 20 knots and way better figures if you slowed down to 10 knots. Then there is Foreign Affair a Chamberlin 14.25 metre powercat that averages 1. 3 litres an hour while averaging 14 knots during bluewater cruises or a 50’ boat I went out on last year that was total luxury at sipped fuel at 12 litres an hour at 10 knots and rode so well there was no danger of spilling our drinks in a two metre slop! Compare these figures with most of the production cruisers on the market today!

Its about time these gas guzzling designs are called for what they are!

Beachboat?

The original boat in this thread looks like a Shannon *** can't remember the letters (SRD?) but it related to the unusual inverted hull shape aft.
Actually I went onboard that boat at the Norwalk CT boat show and talked to the designer.
The hull shape is cool and he says that is has very little wake. The boat is designed to operate from 15 to 24 kts if I remember correctly. The hull shape may have some advantages but the biggest thing is the light weight construction, narrow beam and some restraint in the added "stuff" onboard.
By using smaller engines and moderate tankage the speed and efficiency are better.
I think that this is another example of a light weight semidisplacement boat not too different from Nigel Irens Rangeboat. My point is that the improved performance is not solely the hulls contribution.

All this has me thinking about my own boat. A Ted Hood Whisperjet. Ted cut out the chines with a 6" radius and called it the "quiet chine" yes it is quieter at rest but on plane the beam is a foot narrower. The boat is quite a bit faster than any of the equivilant "blue hulled jetboats".

Speed and efficiency really boil down to load. The Shannon and the Rangeboat are very lightly loaded. I am now looking at technologies to reduce weight on my boat. This winter we replaced the generator and saved 120 lbs.
The spare zincs will now stay at home. The water tanks will only carry what is needed for the trip. Someday I hope to replace the inverter/ charger and battery banks with lighter versions. We picked up about 2 kts at 3000 rpm
from 29.5 to 31.5 allready. I suppose the family has to come along..

Can someone please explain the mochi long range hull...what makes so great ?