Planing in 12s.

Jimbo41 · 13 Dec 2006, 08:06

Roger: "As Cilla would say there's a lorra lorra lost plots going on here,isn't a large part of this being able to get good boat speed and good tactics to get round in front?

A tow is no substitute for sailing...."

Absolutely. No question about it Roger. However, if you knew the boat design better, you could find yourself going quicker, faster if you iunderstand what I mean. Towing a boat can give you a better idea as to how she reacts under these conditions. And it's also a good excuse to get people over for a BBQ....

Jim. N3130 and N3470.

JimC · 13 Dec 2006, 09:05

[quote by=Roger_Brisley link=Blah.cgi?b=Cool,m=1164825767,s=58 date=1165962669] A tow is no substitute for sailing,[/quote]

Exactly so, but equally empirical observation from sailing/racing results is no substitute for repeatable science. The two are complementary.

In terms of success in introducing new classes without them dying after 10 years and gaining International acceptance then the most successful designers of the last thirty years are the Bethwaites. They're also the only people who have a consistent pogram of tow tesing so they have some real data about how hull shapes perform. I don't believe that's a co-incidence.

In my time sailing Cherubs I was never sure who was fast because of their boats, and who was fast in spite of them. Hull shape is really such a small percentage of total performance I've never been prepared to say what is hull and what is other factors. Which is more important, early planing or low drag high displacement speeds? Only one way to find out!

Anyway science is fun and interesting. For some of us anyway. For others its mindless ly boring. But then there are people who don't like going sailing!

Jimbo41 · 13 Dec 2006, 09:33

[quote by=JimC link=Blah.cgi?b=Cool,m=1164825767,s=61 date=1166000717]

Exactly so, but equally empirical observation from sailing/racing results is no substitute for repeatable science. The two are complementary.

I agree there. let's try both.

Anyway science is fun and interesting. For some of us anyway. For others its mindless ly boring. But then there are people who don't like going sailing!
[/quote]

I like sailing and I like science. Surely, we should have time for both postulating and bravado. :B

Jim N3130 and N3470 (N12 - Have a drag on this....

)

angus · 13 Dec 2006, 01:08

Barry · 13 Dec 2006, 05:47

Put me down to lend a hand - subject to the usual conditions - of not sailing my plastic boat(s) elsewhere.

Oh and if over Easter I'll have to be able to bring the dog.

I'm not sure how much wiser we'll be after this but I do suspect it will be a hoot. No real expertise to bring to the party - but I do like BBQ food.

Barry
N3364

Jimbo42 · 13 Dec 2006, 08:34

philipcosson · 16 Dec 2006, 08:58

boing

Jimbo41 · 19 Dec 2006, 09:48

UPDATE UPDATE UPDATE

Ok. proposals being considered by Spinnaker comittee, (says he standing there with sweaty palms).

We shall see.......

Jim N3130 and N3470.

P.S. I'll be down on the water at Spinnaker on the 28th December with Passion Pudding.

Simon Nelson (Guest) · 19 Dec 2006, 07:27

[quote by=JimC link=Blah.cgi?b=Cool1,m=1164825767,s=61 date=1166000717]
In terms of success in introducing new classes without them dying after 10 years and gaining International acceptance then the most successful designers of the last thirty years are the Bethwaites. They're also the only people who have a consistent program of tow testing so they have some real data about how hull shapes perform. I don't believe that's a co-incidence.[/quote]I am not sure I can agree with your conclusion. Firstly, while Frank did a lot of tow testing, I don't think Julian has in recent years. Secondly, the success of the Bethwaite designs on an international basis is more an accident of geography than anything else. I will try to explain.

Australia doesn't have a very large market for high performance dinghies. For the Bethwaites to make money, their designs need to succeed internationally. If you ever go to an ISAF conference, you will find Julian hovering around for the whole time. He is always canvassing, monitoring etc. Take, as an opposite, RS. Their home market is so big that they can go a few years with a design before supply gets greater than demand. They don't need to push the international stuff anywhere near so hard. So, different approaches have produced different boats and different success. You could also argue that the Bethwaite marketing machine has done a better job than any of the others by playing the "long game", concentrating on international take up rather than meeting short term demand.

Don't get me wrong, they have designed some great boats but getting international take up isn't much to do with great design. It's more to do with great marketing and strategy.

Jimbo41 · 20 Dec 2006, 08:08

Simon, how might your very interesting analysis help us? Are you saying there's no point?

Jim N3130 and N3470

Mikey C · 20 Dec 2006, 09:06

I think he was just saying International success and great design don't necessarily go hand in hand!

Jimbo41 · 20 Dec 2006, 09:13

Dead right there Mikey!

Incidentally, do you know where we might be able to get a suitable strain guage for our dragging endevour? Grazz says the association doesn't have a suitable one. Large dynamic range and sensitivity would be required, not an easy choice.

Cheers,

Jim N3130 and N3470.

johnk · 20 Dec 2006, 09:59

Consider getting two strain gauges - one for low speed - one for high. It may be easier to try two boats at a time on a pivoted beam so that one can measure differential drag. The strain gauges would give drag v speed curve for one hull with say 2% accuracy. With two boats, keeping one as a reference design, you could plot % difference in drag v speed to much higher accuracy than by comparing separate drag v speed curves.

Jon_P · 20 Dec 2006, 10:42

bethwaite talks about this technique of 'the 'balance' method of tow testing in one of his books. Keeping one boat as a reference. can't find it at the mo. but will keep hunting.

Jimbo41 · 20 Dec 2006, 12:56

Super! Thanks lads.
I'm currently scouring the internet for a suitable transducer. found one with a 5kN range. Sealed unit. Trouble is, we'd need an amplifier and a radio output to the towing boat/shore. Budget doesn't stretch that far.....

I'm down on the 28th December at Spinnaker to test out Passion Pudding (N3470), so if you lads are in the area, we might be able to meet?

Cheers!

Jim N3130 and N3470.

Planing in 12s.

Simon Nelson (Guest)