30 degrees deadrise ? Why not ?

[xarax]

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 ?

[Willallison]

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

[Nomad]

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....

[xarax]

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 ?

[Nomad]

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

[Sean Herron]

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.

[jfblouin]

Rosborough annonce 37 degres deadrise on theirs RIB

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

[cyclops]

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.

[Sean Herron]

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.

[cyclops]

Weird stuff never dies.

[lazeyjack]

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

Please expand

[RANCHI OTTO]

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

[lazeyjack]

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.

[jfblouin]

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.