Sailing Faster than the Wind

[Kiteship]

Planing multihulls

Parlier was also taking it easy, that was his first major trial offshore & he was by himself. He also broke some parts on his boat during the Transat. The boat is new, they are still testing it. Whats the average speed got to do with anything, he could have been going 20 knots for like 1 hr, but then the rest of the time he could have been going around about 10 knots, this would mean that he would have a lower average speed. Average speeds cannot be used to tell accurately whether a boat is planing or not. The accurate way is to have the actual hull speed of the boat & if it passes its hull speed this means that it is planing.

Both your post, and the one which follows (Grob) are in response to a post about planing *upwind.* I know a little bit about planing multihulls, having built and sailed a number of successful ones myself--the first ones many years ago (see http://www.dcss.org/speedsl). There's no doubt that Yves' boat is spectacular, and that it will plane. I suspect it may even plane upwind.

The point of my post is that this has yet to be demonstrated. Some of Grob's information is mistaken (though it comes from reputable sources); the boat begins to plane at about 14 kts, not 27 (a little math and some knowledge about the physics of planing will bear this out). Yves himself claims the boat has a noticable drag hump at 16-20 kts, which is in keeping with what one would expect from such a planing cat. The fact that the Transat was experimental, first trip, etc is not germane--the boat can certainly plane and *will* sail fast; the question was--and remains--can she plane upwind?

An 8 kt average during the Transat certainly does not mean the boat made the crossing at 8 kts. What it does indicate is that the boat *likely* did not spend much time in excess of 2 1/2 times this average speed; i.e.: 20 kts--truly planing--during this upwind race.

yachtie2k4's post claimed that he "thinks" that Parlier's cat can plane upwind. Mine was to claim that this hasn't been demonstrated as yet.

Cheers,

Dave

 

[yachtie2k4]

Dave,
What I meant was that I think it might be able to, you are right in that it hasnt been demonstrated yet though. I think that once they have tuned Parlier's cat, it might be able to plane upwind, hopefully because this would be one of the first multihulls to do so.
I do now understand your point of view
Regards.
Rob

 

[Kiteship]

I designed a kite-powered planing catamaran which planed to windward (just), in 1988. Photos on www.dcss.org/speedsl. It was optimized for off-wind speed, as is Parlier's cat. Planing hulls are often a tough compromise; you trade off a narrow performance window for high speed.

FWIW, windsurfers have been planing to windward for 20 years, beginning with the Div II boards and olympic boards in the mid 1980's. IMO, you won't find many multis planing in any conditions, because by and large, they don't need to. Long thin displacement hulls are extremely efficient in all but the very fastest speeds--far, far better than planing hulls at low to intermediate speeds.

It's the monos which can effectively use planing hulls, not multis. This is a feature of multis, not a bug.

Dave

 

[coiler]

You have forgotten one brand new 36 footer, FULL PELT X.
Under IRC the z86 Maxis rate 1.648 and Mari Cha whilst not having an IRC certificate is thought to rate about the same.
So imagine a mono hull with an IRC rating of 1.704 !!!
The yacht is off the Richter scale.
FULL PELT is 36ft long and weighs in at 1600kg and 800kg of that is the keel bulb which cants 55 degrees(110 total). The hull is made of wet lay carbon/nomex, and she has a Proctor carbon rig.
She has better displacement length ratio than a 49'er.
FULL PELT will becompeting in the Round the Island Race at the end of June; apparently this beast does meet the stability requirements!
The true objective of the designer Jo Richards is that FULL PELT will plane upwind

I think that you forgot to mention that you copied this from

http://www.bangthecorner.com

 

[yachtie2k4]

ohh, I thought I had put that in, I am sorry Coiler. I did take it from www.bangthecorner.com because it is a good site. I will remember to acknowledge my sources next time.

 

[yachtie2k4]

Now, if only I could work out how to edit my post to properly acknowledge www.bangthecorner.com

 

[yachtie2k4]

the only problem with Bang The Corner is that it doesn't have any information on boats in Australia

 

[yachtie2k4]

Ahh well, it appears I can't edit my post about Full Pelt, so for post #5 in this thread I acknowledge www.bangthecorner.com it is a great site, but there is only 1 problem with it and that is that it doesn't have any information on Australian boats/races that I have read so far. But, apart from that it is a great site, well done Coiler.
Rob

 

[coiler]

Ahh well, it appears I can't edit my post about Full Pelt, so for post #5 in this thread I acknowledge www.bangthecorner.com it is a great site, but there is only 1 problem with it and that is that it doesn't have any information on Australian boats/races that I have read so far. But, apart from that it is a great site, well done Coiler.
Rob

thanks that is enough plugs and links, i will get flamed for advertising!!

i would love to write more about aussie yachting,i did do a big piece on the sydney hobart with dave kellett

http://www.bangthecorner.com/default.asp?m=da&id=10319&nodate=1

i would happily do more if you or any one else for that matter has some ideas let me know

coiler@bangthecorner.com

p.s. i will join this forum it looks like a good source of info!

 

[SailDesign]

p.s. i will join this forum it looks like a good source of info!

As long as we get credit and attribution

Revenge will be swift, but probably not that painful...

Steve

 

[yachtie2k4]

yes, as long as we get acknowledgement Coiler, I can give you lots of information about australian sailing through the year, but at the moment, not much is happenin cause its winter