Deep V hulls

[muckypup]

While looking around, I have seen quotes which imply that a deep V hull is best for seakeeping, while a shallow V hull is only really good for pulling water skiers along.

Is this true? What is the different in real terms between the hull designs?

Steve

 

[rich]

A deep V will give you a softer ride, ie less slamming,and ankle jarring.

 

[BrendanS]

In very simple terms, a deep v hull has amongst the best sea handling of high speed boats. You need lots of power to push it along at speed.

Many hull designs have relatively deep v at front to assist punching through waves and reducing slamming, with the v decreasing towards the stern to assist with planing.

There are other designs such as my own hull, which has very deep v at bow, but very low v at stern, and with steps in the hull and all sorts of other design features which means it planes incredibly easily and efficiently, handles most rough conditions at planing speed easily, but handles displacement speeds like a deep v, and turns on a sixpence with no slippage at all.

Shallow v hulls have their place, but not at high speed in anything other than smooth/moderate conditions. The displacement and semi-displacement hulls can be low V or moderately high v depending on their use and function.

 

[Sneds]

Is there a figure, in degrees, that would define one from the other?

 

[gjgm]

pretty comprehensive reply from brendanS. I'd add that the the deadrise angle is measured at the stern (the V at that point).24degrees is about as steep as you are likely to see it-good for seas, but needs more power to keep on the plane and higher speed to get on the plane. The boat is only efficient when on the plane, so to some extend, the lower speed you can plane ,might be better. Other than pro powerboats, I think its usually only a few of the smaller sportsboats that have 24degrees. Most sportsboats are about 21/22, though you do see some down at about 18. Bear in mind the shallower the V, the more use the hull might be for accomodation etc.
Specialist skiboats, and I m talking about competition boats, are very flat- well they are on lakes. They need quick and stable speed, and no wake. The Regals I had chucked out a huge wake,cool for wakeboarding, but not always popular with the wash police. I somewhat doubt I could spot an extra degree in deadrise under way, but probaly pretty fair to think 22 will be better than 18 off our costs. Still, a little marketing brochure blurb in there too...!

 

[Xenopus]

Just speaking from experience, our last boat had a 21 deg deadrise and our current one has 24 (real racing hull territory - its also long and thin which helps a great deal too) - there is an enormous difference, in 5 years I've never had to slow below 35 kts due to conditions even tho we've been caught out on occasion (generally if there are horrid short unpredictable seas the best bet is to go a bit faster, trim appropriately and go over them I've learned in this boat). For us it has made a big difference to our boating pleasure. As stated elsewhere the penalty is the need for big engines and the fact that the hull really doesn't start to perform well until relatively high speeds are reached (35-45kts) and it obviously will not plane at low speeds. In addition these sorts of boats tend to have limited accomodation, ours is 36ft but had the accomodation of something like a normal 26ft - only good for a long weekend with the family. As I say there's a proviso that this is based solely on my own experience.

cheers,

 

[muckypup]

Interesting... I had not even considered the accomodation angle of the different hulls...

Can you tell by looking at the boat the deadrise, or would I have to research the model?

S.

 

[Xenopus]

Hi - you can only measure it out of the water so much easier to research the model. The really deep Vs will have racing backgrounds eg Cigarrette, Dragon, Hunton etc - possibly the Faireys and their relatives. I'm sure someone will know for certain.....

cheers,

 

[BarryH]

Don't just look at the deadrise angle. My boat has a deep'ish vee right to the stern. The keel is carried along way forward. It gives a good soft ride in a short chop, but can be a little unstable at rest. It has two massive reverse chines that run 3/4 of the length. When I say massive the are almost vertical blades for half the length of the boat. Exellent in turns as the boat just won't slip sideways and the forward parts deflect spray.

So in short look at the thing as a whole and not just "components of the hull.