The Hull Challange

Gludy

Active member
Joined
19 Aug 2001
Messages
7,172
Location
Brecon, Wales
www.sailingvideos4us.com
Here is the boat rating from the RCD based on the sea worthiness of the boat:-

“A” (Unlimited Ocean) STIX Value >32 - adequate to withstand up to a force 10 gale, with average waves of 7 m height and eventual wave heights of 14 m.

“B” (Offshore) STIX Value >23 - adequate to withstand up to force 8 winds, with average waves of 4 m.

“C” (Coastal) STIX Value >14 - adequate to withstand up to force 6 winds , with average waves of 2 m.

“D” (Local) STIX Value >5 - adequate to withstand up to force 4 winds, with waves of 0.5 m maximum.

I would be amazed if you can find any class A rated boats with planing hulls anywhere in the lesiure market.

The trader is Class A, the Squaddies of the same length and weight are class B

I frankly think that is game set and match!

However I am not saying nor have I ever said that planing hulls are inferior .. they are not... there is a balance of factors that each has to choose from all I have demsontrated is a single point that should have been accpted a few hundred post back but the real discussion has not even begun.

I would liek a seriuos discussion of hull characteristics, from which we all could learn.
 

KevB

Active member
Joined
4 Jul 2001
Messages
11,268
Location
Kent/Chichester
Visit site
I assume you are only interested in "ocean" going vessels? If I was going to buy a boat with this in mind the information you posted would be useful. But I wouldn't and neither will 99.9% of pleasure boat owners.
Now if I wanted to race around the IOW then your stats mean didly squat and a Sunseeker XS 2000 planning boat would be a better boat than any displacement or sd boat.

And here are the stats to prove it...

Principal characteristics
Length – overall (incl. pulpit): 11.85m, 38'9"
Length – hull (incl. platform): 11.85m, 38'9"
Length – waterline (@ half load): 10.17m, 33'4"
Beam (max.): 2.34m, 7'8"
Height above waterline (incl. mast): 1.46m, 4'9"
Height – overall (excl. props): 1.89m, 6'2"
Draft to keel (excl. props): 0.65m, 2'2"
Draft (incl. props): 0.80m, 2'7"
Displacement (@ half load): 5000kg, 11020lb
Fuel capacity: 470 litres, 103 GB gals, 124 US gals
Fresh-water capacity: 8 litres, 2 GB gals, 2 US gals
Propulsion: Twin Trimax surface drives
Engine options: 2 x Yanmar @ 354PS (257kW/350hp), 2 x Yanmar @ 425PS (309kW/420hp)
Fuel options: Petrol/Diesel
Generators: Not applicable
Maximum speed up to 65 knots*
Cruising speed: 40 knots*
Range: 180 miles*


Horses for courses.
 

Gludy

Active member
Joined
19 Aug 2001
Messages
7,172
Location
Brecon, Wales
www.sailingvideos4us.com
Kev
I do not know hwo you are arguing with because its not me ... Of course horses for courses ,,, I have never implied anythin different.

All the multiple thread have developed into is the one issue about sea worthiness and that frankly is over because the RCD directive is just that a class of seaworthiness.

Nor can you jump to assumptions that I only look at ocean going boats - I do not. It is simply one factor amongst many.
 

rickp

Active member
Joined
10 Nov 2002
Messages
5,913
Location
New Zealand
Visit site
I suspect the RCD is an effort to distill sea-worthiness into a set of rules but as with any set of arbitrary rules (particularly from the EU) I imagine there are ways of meeting a particular class without giving the benefits so ascribed. ie., I bet manufacturers can play the 'RCD game' and get an 'A' hull without it necessarily being better than a good 'B' hull. I believe such comments have been made about AWB saily boats in the past.

The EU meant it as a 'guide to consumers', so I personally wouldn't take much notice of it, and certainly won't be taking an 'A' boat out in F8 winds and 4metre waves, just because the EU's RCD rating says I could.

Rick
 

Chris_d

Well-known member
Joined
15 Jun 2001
Messages
4,721
Location
Oxfordshire
Visit site
I think your twisting the regs to prove your argument, to get a class A rating its not just the type of hull that is considered it has to have a range of more than 500miles or something, so the Trader only qualifys when in displacement mode anyway, to get the range. There is also a requirement for a minimum anount of water to be carried so as to be self sufficent etc, etc... A planing boat could be engineered to obtain a class A rating but the manufacturers don't bother because most owners don't require huge tanks etc.. and the resultant loss of perfomance.
 

jfm

Well-known member
Joined
16 May 2001
Messages
23,839
Location
Jersey/Antibes
Visit site
Re: The Hull Challenge ABCD categoroes

I agree Rickp's comments. Also these are broad categories. The Sq58 and Trader 575 that are being compared could be nearly identical, if one is at top of its range and other is at bottom. In fact, common sense says the 575 must be at the bottom of A (no insult intended, it's small for an A boat) and the Sq58 must be at the top of B because there are (good) 25 footers classed as B. If you are seeking to prove material absolute differences between 2 boats you can do it between an A and a C but not between an A and a B. Common sense is loads more use than relying on A or B classifications
 

JEG

Member
Joined
13 Jul 2001
Messages
220
Location
Surrey
Visit site
Re: The Hull Challenge ABCD categoroes

Don't know about RCD rating but might a catamaran hull form be superior to dis/sdis/pl?
 

victoraspey

Member
Joined
26 Oct 2003
Messages
519
Location
Emsworth
www.mcpmarine.com
Re: The Hull Challenge ABCD categoroes

Catamaran hull form can be U shaped displacement, Semi displacement with U shaped front with flat section behind or v shaped planing. All catamaran hull shapes are not the same and beam also comes into equation.
 

victoraspey

Member
Joined
26 Oct 2003
Messages
519
Location
Emsworth
www.mcpmarine.com
Re: The Hull Challenge ABCD categoroes

Width is a stability consideration but excessive width is only necessary on a sailing catamaran to overcome the huge capsize forces generated from the sail. A motor catamaran beam length ratio of 3:1 is widely regarded as ideal -high performance offshore power catamarans with narrow beams show that a wide beam is not necessary on a motor catamaran.
 
Top