NZ 8.5 Rule

How about a thread just for this class ?

 

I'll start, is it becoming apparent yet wether cat or tri format is dominant ?

 

8.5

Great idea! Here is the Rule for those that aren't in the know:
http://www.multihull.org.nz/open-8.5m-class/8.5-rules-1008.htm

Seems to me the beam max is fairly narrow for a modern trimaran design and just about perfect for a cat...

 

A stretched B24 would fit just fine into that rule.

 

It's kind of your mantra, OS - "No matter your sailing needs, there's a Bucc for that" ;-)

NTTAWWT !

Mike

 

Nttawwt !----????

 

Not That There's Anything Wrong With That.

(usually used in a context of political correctness, as in "I think those two women got married last weekend... NTTAWWT" ;-)

Edit again - in an Ozzie context - "those guys got so drunk after the rugby game that they slept together again..." ;-)

Mike

 

Who's winning ? cats or tris ?

 

Cats have won both the Nationals and the Coastal in the last 5 years or so.

The rule seems to favor Cats slightly in terms of results, however this might be because there are more of them on the race course on any given day (generally about 5 Cats per Tri)

There are four Tris so far designed specifically to the rule launched and one more about to be built. One of the Tris is a bit off the pace and doesnt race (owner building a cruising Cat), one was very quick but isnt racing (owner coaching an Olympic team at the moment) the other two just launched and showing solid potential so theres hope for the "Tri camp" yet!!!

There is also some Farriers which are very quick on the right day.

 

A stretched B24 would be a weapon built to the rule!

would you stretch it to 8m or 8.5m tho? do you think the scantlings would take the extra sail area ok?

Adding 2.5m to the floats would be interesting!

 

So Sam would it be fair to say the beam limit is handicapping the Tri's ?

 

I think so! A successfull tri has to be a little wider to perform well in this class. Thats one of the big critic points all over.

Michel

 

well to be honest the Seacart 30 is the fastest 30ft tri (that I know of???) and its only 6m wide. It wasnt designed to any rule so my opinion is the width restriction isnt an issue

Very few 8.5m Cats would be 6.5m wide??? prob about 5 or 6m would be the average?

 

GBE's are 5 metre Boa as is Tigre. Attitude 5.2, TC 8.5 5.5, Deeds is 5.6, Borderline 6.3. The new F85SR is 6 metre boa, although that may be influenced by folding. Lucifer and Stealth Mission 6.5. Quite a variation.

 

Yes I have pondered that possibility for several days now. I think the scantlings would be just fine. They have stood the tests of time. Most Buccs were built of 1/4" ply as it was more available, many were even built in Douglas Fir Ply as it was cheap and obtainable then. I have never heard of one breaking up at sea----only hitting things

The Bucs BOA is almost 6M. Increasing it to 6.5M would add more than 2M of alloy tubing and stainless steel to an area where extra weight and windage would be a disadvantage without much gain.
Tilting the floats out at the keel line and reducing the dihedral on the cross arms would effectively add a little to the beam without any penalty, while keeping the rig more upright. Reducing the angle on the buttocks area, (Like Miranda), is accomplished with little addition of weight by simply extending the keel line and angling the transom. No need to overdo it. The alternate spade rudder would be just fine.
I don't see any need to extend the floats. Again an extra addition of weight, windage and wetted surface. Who is to say that the extra length forward wouldn't produce a greater moment to trip over when burying a bow.
Samnz has demonstrated how well the bog stock Bucc handles that.
Now if the mast is kept to the stock length, more sail power can be derived from a larger fully battened fathead sail and a rotating mast, rather than a taller mast and sail with it's extra tipping power, even though it's higher aspect ratio is theoretically more efficient. A sideways tilting mast would be a good idea too. Again ask Samns.
The prodder (bowsprit) can be extended to the limit of the new rule and be of benifit as the shallower angle of the forestay provides an upward component of the sail force which would help to keep the bow up in a bad gust.
And the last, but by no means least, is a much more efficient daggerboard, or canted daggers in the floats like Miranda, or the ones Bruce is fitting.
I noticed in another thread that a poster had a B24 in the early 1960's which would have made it a really old design indeed. This is not true.
The B24 plans were first issued in Dec of 1969. My set of plans were set #63 and were received in March of 1970. On the water it is still a very modern looking boat and still challenges the latest designs.