30 degrees deadrise ? Why not ?

I have seen studies calculating the impact of water at hulls with 30 degrees dihedral edges , and it is greatly reduced indeed. However , I don t know any production boat (please correct me in this ) having a hull with such a deep V. I suppose that the difference in lift force on hulls of 27 or more degrees is so big that excludes the use of , say, 30 degrees deadrise in commercial boats . Is it so ? Why nobody uses a 30 degrees deadrise instead of a semiplaning hull ?

 

Smuggler boats, in New Zealand, use a 30 degree deadrise hull in one of their 20-odd foor runabouts

 

Would need alot of power and some serious lift to push that kind of Deadrise... As for the 30 degree vs. semi displacement each has it's place. If you want a semi-displacemnt you proably want less draft, more stable hull, and more efficent/less power. Deep Vee is more high performance related....

 

May be a central pad (or two lateral pads) would improve the lift on such a hull, and on the other hand would preserve the so desired low water impact characteristics . Any thoughts on that ?

 

Flat pads can be great in many applications, they give you speed, running angle and effiency, and stability but they in offshore applications defeat the purpose of a Deep-V. The flat pad will make for a harder ride with an outboard boat if it comes out of the water. It's all compromise

 

Why Not...

Hello...

There is no why not to 30 degrees of deadrise - even followed all the way aft to the transom...

The trick is to provide enough area in the strakes to lift the bow up and over the bow wave - this matched with power...

Also a good bit of antihedral (my term for a 3 degree - or more - downturn in the chine) and again a good bit of surface area in the chines to keep that thing up...

Long trim tabs...

As for ride pads - never fell in love with them - get a bit skiddy in a hard turn where a full run fairbody provides good and predictable bite...

I am just now thinking of a great old book - something something 'high speed planing craft' - sorry - it really goes in depth - per the 1970's - Don Aranow (sp) Donzi - also Sonni Levi (sp)...

Time for bed...

SH.

 

Rosborough annonce 37 degres deadrise on theirs RIB

http://www.rosboroughboats.com/rib/ribmain.htm

 

When you build a CONSTANT deep V of more than 27 degrees it should be with one thought in mind. I want a possible chance of surviving in sea conditions so bad that I never should have got myself in this position.--- + 30 degrees and more are for the few boaters who want to boat in suicide weather and give Death, the finger, and think they are going to make it back.

 

Measure your backside

Hello...

I can take a deadrise angle at any station - what I would concern myself with is the ride plane at speed - the aft third or so...

37 degrees is great if you are powered by a helicopter engine and you have inflated chine tubes holding you upright at the dock...

Otherwise go Don Arranow or Soni Levi researching - hell - even pastel jacketed Don Johnson opinions...

By the post date - is this thread not dead yet...

Popeye Chicken - YUM....

Burp...

SH.

 

Weird stuff never dies.

 

deadrise where

deadrise, where, ? aft uncommon and of no use, forward, 60 dgrees in fast planing hulls (see the designs Street)

Please expand

 

Why so a deep vee bottom deadrise ?
20 deg. + 2 lateral annexes give enough lift to have a well-balanced boat.
No jumps, and first of all SECURITY.
Extreme boats can be safe.....

RANCHI OTTO

 

in my long experience, , building and using deep V planing boats, , anything over 20 degrees aft makes the boat unstable down wind and sucks up power
I prefer a deep forefoot, for soft riding in a chop . with sections flattening aft, for easy lift and stable ride, with inbuilt gullwing chines and MINUIMUM strakes, just two short ones about one third of the way up from centreline . These not for liift so much as directional stability Multiple and long strakes make the ride hard.

 

Rosborough reply me that theirs boats are 33 degres deadrise

Thank you for your interest in our Rigid Hull Inflatable Boats. We originally designed the Rough Water™ 30’ to meet and exceed the need in the Commercial RIB industry for a vessel with a larger personnel carrying capacity as well as being able to maintain higher speeds in rougher conditions. With this being such a success we have decided to venture into other size Rigid Hull Inflatable Boats. The Rough Water™ 18 that you viewed at the Montreal Boat Show was our prototype for that size; at this time however we will not be developing a unit of this size.

Our Rough Water 26’ however is available. We have one unit in stock powered with twin Mercury 150HP outboards. I apologize for the typo on pour website regarding the deadrise; this unit has a constant deadrise of 33º. This Unit with the Below Equipment is $72,000 Canadian.

Equipment List
One Piece Hand Laid Hull
Fiber Glass Stringer Grid
Molded Non-Skid Decks
22” Hypalon Tube w/
2– 80 Gal US Aluminum Fuel Tanks
Fuel Filter Water Separator
Hydraulic Steering
SS Destroyer Wheel
4” illuminated Compass
8 Gang Marine DC Breaker Panel
12V Navigation lights
12V Horn
3” Bilge Blower
Forward Post
Aft Tow Post
3 Aluminum Deck Hatches
Center Console w/ Windshield
Standard Horizon VHF w/ 5’ antenna
Dual 27 Series Marine Batteries w/ Select
12V Bilge Pump 1500GPH w. 3 way switch

Power– Twin 150HP Mercury EFI Counter rotating Outboards with SS Props mounted on an Aluminum extension Bracket.