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All multis are about Power to weight

 

and waterline length. assuming same power to weight ratio longer boat wins.

 

Looking at the pics now it would seem logical that the main hull be chopped off where the floats end, the bit hanging out of the water is dead weight anyway.

Then you get same waterline length, same SA and the way the rule works a lighter boat (lighter min weight)

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If you want to be the fastest 8.5 in NZ at the moment you need to buy Dirty Deeds or a copy of it.

 

Yes - I agree from looking at racetrack DD is "the" 8.5 boat right now. However Predictwind wasn't far behind it (again from racetrack) - do you buy the idea that this newer F boat (if built ultra light and sailed well) it might be faster still? Has DD been modified since early 2009 when Predictwind last raced?

 

I don't know - I'm a programmer not a boat designer and know f-all about multi's - so I'm looking for some more informed opinion here...

 

DD has had modifications made to stiffen their rig. I believe these changes have made them faster across the whole breeze range.

 

Need for Speed is also being sailed by Jon Bilger who is a very good sailor.

I believe his ability probably over states Need for Speeds actual pace to some extent.

 

Also under the 8.5 rule the 8.2m can be slightly lighter, which in a boat this size could be quite critical.

 

The new F8.5 has 42 m^2 of sail whereas Deeds, attitude, Lucifer are nearer 50-55 m^2.

 

All multis are about Power to weight

 

Not necessarily, more efficient multihulls can be faster with less sail area.

 

However, more sail area can be added to the F-85SR if anyone wants, but because of the mast height limitation it has to go on sideways. This gives low aspect 'barn door' sails which look old fashioned in my eyes, and I think they are bone ugly.

 

So anyone can add a squat mainsail if they wish, just don't send me a photo! Low aspect sails are also less efficient, so any gains will not be significant, and too much roach or an excessively wide squaretop tend to add handling problems.

 

Ian Farrier

Farrier Marine (NZ) Ltd.

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All multis are about Power to weight

 

and waterline length. assuming same power to weight ratio longer boat wins.

 

Looking at the pics now it would seem logical that the main hull be chopped off where the floats end, the bit hanging out of the water is dead weight anyway.

Then you get same waterline length, same SA and the way the rule works a lighter boat (lighter min weight)

 

But it would be slower overall. My boats are designed for all round performance, which includes going to windward in rough seas, and high performance in light airs.

 

Overly long floats are a mistake. There's more leverage on long bows, so they need to be stronger/heavier, with more windage. Overlong sterns are also heavier, can dig into following waves too much when running diagonally across waves to depress opposite bow, plus they tend to aggravate pitching going to windward in a chop. It's all a matter of balance.

 

Ian Farrier

Farrier Marine (NZ) Ltd.

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high aspect mains are more efficient so it would be better have taller rigs (but we wont go there) - square tops do have a degree of gust response which makes for easier trimming. Almost every boat that has had a square top addition in the 8.5 fleet has had a jump in performance except in the very heavy. Partly I think this is that the GBE's, with that extra area up high, pop a hull a bit earlier.

It does make you wonder why alingi had such a large square top when there was no restriction on rig height -maybe they had to keep the power low (with a lack of righting moment? -they were already flying a hull in 4-5knots) for upwind but still wanted the extra area for downwind.

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