16 Degree Deadrise

Yes RANCHI OTTO:

I have been busy.....
Will be sending you a private message.

Cheers.

 

Hi
I have been involved with rib designs since 1984. I dont know the seastate which are mentioned in that area but the best combination for the size boat (8 - 8.5m) going offshore is a 20 - 22 deadrise. Ging up to 23 is acceptable but all depends on the hull design. If the chine beam is designed in such a manner to assist the boat with early planing, its great. A 16 deg deadrise on the boat mentioned - wear a kidney belt or fit the boat with suspension seat.

 

This is the cross sections of the REFOLO ASD (Arrow System Design)

length = 6.2 m
breadth at transom = 2.4 m
power = 1x205 hp
speed = 45 knots

deadrise = 22 deg.

 

Nice hull, Ranchi. A frind of mine (unluckily dead in a terrible accident) used that kind of hull forms more than 15 years ago, here in Vigo. He produced several patrol boats for the Customs, around 12-14 m long (if my memory doesn't fail me) which performed pretty well. I think there are still some of them around.

Cheers.

P.S. Is your site http://www.ranchidesign.com/ with problems? I cannot reach it.

 

Kobus,
What would you say it would be a nice chine beam for a typical 7.5 m rib, for it to go easily in the planning? I have experienced problems with one having 18,5º deadrise and 1,94 m chine beam at the stern. Not easy to be brought into plane with an estimated 70 HP/Ton (jet)

 

To Guillermo..

The boat was the OCEANO ASD 9 (see my gallery) built by my ex-friend J.Barreras Larramendi in Vigo.
The steel boat reached the speed of 60 knots...

After the first boat, J.B.B. copied my ASD with poor success....(friends!!)

I have spent long time in Vigo and Galicia with my friends Adrio (father and son) screw manufacturers.
Galicia is fantastic......only beautiful souvenirs! (people, food, nature etc.)
I have visited more than 50 countries but Spain and Galicia......

My new web is under construction. For my designs see my gallery and for ASD tech. specification the web www.adragnayachtdesign.com

Juan is dead? we are speaking of the same person?

 

This is the OCEANO ASD 9 with me and my ex-friend J.L.L.B. on board during sea trials in the Vigo bay....

 

Yes, José Juan Barreras Larramendi had a terrible car accident more than 10 years ago and died instantaneously. His son José kept on with the Oceano boatyard, but finally desisted. I see him here and there from time to time.
I didn't know the Oceano boat design was yours.
Whenever you come to Galicia, you know where I am. I'll be delighted to meet you. We'll enjoy some 'marisco' poured with 'albariño' wine....
All the best.

 

Thanks Guillermo,

I'm sorry for the dead of Juan. Copy patented hull shape is nothing if compared with the tragedy for the family...

ciao Otto

 

Holy crap Ranchi ! Do I count 6 V8 Evinrudes on the back of that thing !?!?!

Absolutely fabulous - bugger the fuel consumption... all boats should suck it like there's no tomorrow!

 

Yes....6 outboard engines x 275hp.
To reach the speed of 60 knots in Ocean with a STEEL boat...no other possibility!

Consumption during sea trials....500 lt/h gasoline abt....!

With the ASD (Arrow System Design) hull no problem to install them.

 

Otto:

What is the purpose of the bulges toward the aft of these boats? Do they offer static stability, or is there more to them?

~ ALowell

 

PROBLEMS OF TRADITIONAL HIGH SPEED HULLS
---------------------------------------------

The evolution of engines and propulsion systems has not been accompanied by innovative hull designs giving support to the concentration of weight in the aft part of the high speed hulls.
The main problems of classical high speed boat are as follows:

Porpoising phenomenon at all speeds due to difference between the longitudinal center of gravity and the longitudinal center of buoyancy. The distance between these two centers it too large in the traditional "deep vee" hulls because this hull shape is not suitable for the modern systems of propulsion.

Longitudinal trim angle at running condition. The difference of the two longitudinal centers, as described above, generates a boat running with an important trim angle. This is a handicap because the propulsion is working an inclined flow with loss of efficiency. Visibility and bow acceleration in waves are other negative points.

Large heeling angle by steering leading to loss of stability. This phenomenon is well know and is due to the important deadrise angle of the bottom. The lack of volume in this area forces the boat to extreme heeling angles with dangerous decrease in stability. If these problems are at an acceptable level for sport boat drivers, they represent an open problem for military boats.

Concerning military craft, "deep vee" hulls are not able to withstand overloading in weight (ammunition, troops. fuel oil, etc.) due to lack of immersed volume of the hull.


ASD (Arrow System Design)
--------------------------

ASD (Arrow System Design) is a hull shape invented for the modern propulsion systems and is able to avoid problems deriving from high speed.
The ASD (Arrow System Design) hull consists of a central deep vee hull having two special shaped annexes in the aft.


ADVANTAGES OF THE ASD HULL
------------------------------

The longitudinal center of buoyancy is closed to the longitudinal center of gravity well aft, allowing the boat to run parallel to water at high speed. The propulsion system works at optimum efficiency and in favorable conditions.

The heeling angle of the boat is not in excess of 5°, thus allowing very secure and stable maneuvering. The two lateral annexes with their optimal shape, reduce drastically the heeling angle at fast turning. I've tested the VILLE DE CAVALAIRE ASD at 100 m.p.h. without touch the throttles by full steering..... (picture of the boat is in my gallery)

The fore part of the boat is relatively thin with a high-placed chine. In this way the boat has an optimal response in rough sea contitions.

High stability in all sailing conditions due to the two annexes that give very high values of GM.

The ASD hull is very receptive to an overload in payload with no substantial decrease in performance due to the high value of waterline surface.

 

In my Forum gallery you will find the video of the NAJA ASD during steering trials at 50 knots.

The boat has the following main dimensions:

Material > aluminum

Length o.a. > 12.0 m

Power > 4 x 300 hp

Speed > 52 knots in tropical conditions

sold 40 units to Gulf area country)

 

This is the boat: