<img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" /> Where are you getting this 800mm from?

1.10 The gennaker boom (also referred to as a spinnaker pole)

1.10.1 The length of the gennaker boom shall not be more than 3,50 metre.

1.10.2 When the aft end of the gennaker boom is located in front of the vertical passing through the leading edge of an unrotated mast, than the distance between the fixing point and the leading edge of the mast is considered to be part of the gennaker boom.

1.10.3 In contrast to ISAF rule 64.2, the gennaker boom may be fixed to the forward beam.

1.10.4 The gennaker boom shall be fixed and sit approximately on the longitudinal centreline of the boat.

The current SCHRS measurement rules have the 800mm rule. As you will not be racing under SCHRS, this will not be a problem for you at Zandvoort!

Sorry about that I knew there was this rule somewhere. I just forgot where!!

I would guess that if you get best possible cut for your gennaker AFAIK you need as long as possible boom. And at least in Blade the front beam is 2.35 m from bow thus 3.5 m boom will brake this 800mm rule. I guess that newer Stealths brake this too, someone could measure this?

So with gennaker booms rule "the longer the better" applies thus size matters no matter what she/boat has told you <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

--
Valtteri

On a Blade the 800mm rule equals a pole length of 3.45 meter.
So in case you want to race under Isaf or Texel rating this is max. But I don't think you will notice this small difference.

Geert

Please remember we are reviewing (and very close to completion) of the SCHRS rules for adoption later this year.

Hi Geert,

Where this distance comes from? If I calculate things correctly the beam will be behind bulkhead at station 8. The distance between stations is 30 cm and the first was 25 cm, thus the main beam is from 2.35 m from bow so with 800 mm the max pole length would be 3.15 m. Actually the wave piercing bow will add 5 cm to bow length, so max length would be 3.2 m.

This is of course from memory and I can't measure things today =)

--
Valtteri

I did measure it on my own boat, but it is also from memory.

But you make a small mistake, you are supposed to add 800 mm to the diagonal distance from beam to hull end, see picture.

In your case it would be:
diagonal distance is: sqrt (2,35^2+1,1^2) =2,59m
Add 0,8m and the distance is 3,39m. I would say close.

Geert

And this is exactly one of the main reasons why the F16 class rules didn't adopt the 800 mm rule as used by ISAF and Texel. It is an eternal source of errors. Much better to have to just one single spi pole length as the F16's do. Also this is much more fair in racing as well.

Scooby are you taking note of this ?

The 800 mm will force different pole length to different boats within a Formula class. If your beam is relatively far forward as on the Stealth F16 then the SCHRS / TEXEL 800 mm rule will force you to sail with a 200 to 300 mm shorter pole then crews sailing for example a Blade F16. In effect the spinnaker will be much closer to the jib luff and the spinnaker slot will be about 20 % smaller. The spinnaker will breath less freely.

THIS IS A PERFORMANCE ISSUE !

This (stupid) schrs/texel 800 mm rule is actually enforcing INEQUALITY between formula boats that should really be expected to be equal.

And this is actually the most important reason why the schrs / texel was discarded for th F16 rules. We wanted to have the most equal performacing boats irrespectibally of make or mainbeam location. The second most important reason was the eternal confusion that the 800 mm rule gave and the troubles in getting an accurate measurement.

So Scooby you will now understand why I'm a passionate supported of improving the SCHRS on this particulat point.

So how did the F16's arrive at the 3.5 mtr pole lengths.

Pretty much I made a model of a typcial F16 boat and I used that model to run performance numbers on when optimizing the boat and the class rules. This boat had the mainbeam exactly halveway down the hull which is where most designer try to place the mainbeam. Then used the calculation method as supplied by Geert in a earlier post and rounded off the number downwards to one decimal. The end result was 3.5 mtr (from 3.53 mtr). This was an excellent result as the cube-square law predicted full equality with the F18 (spi pole typical F18 = 3.80) when the F16 poles were about 3.44 mtr length. I split the difference so to say.

So this system worked out well both in F18 equality as in MODELLED average adhearence to SCHRS / TEXEL if the F16 spi poles were 3.5 mtr in length. And so that number was used in the F16 class rules.

Now all F16's would be equal to eachother irrespectable to the mainbeam position and they would be equal to the F18's as well (in this respect). Additionally, the same spi/pole/snuffer design could be used on all F16's and this is appreciated by part suppliers and sailors alike (second hand gear)

All this are advantages of the fixed length rule over the 800 mm rule. And any time I get the chance I propose to the handicap systems that they adopt a similar fixed length spi pole rule for each size spinnaker. It is easier, more fair and alot more interesting to the sailors looking to use secondhand stuff.

One additional quirck of the 800 mm rule is that for example it allows 17 sq. mtr. spis on both a 18.99 ft long cat as well as a 16 ft long cat, but doesn't allow these boats to use the same spi pole length. Then how on earth is the 16 ft boat ever to fit that area of spi to its platform ? especially when it typically also has a significantly shorter mast ? Afterall you have taken away a large portion of its foot length (distance pole tip to sidestay).

So scooby as you will understand my proposal to the Texel / ISAF systems is too just replace the current spi/pole rules by something like.


boats up to 16 ft : max spi are 17 sq. mtr. max spi pole length 3.5 mtr
boats up to 19 ft : max spi are 21 sq. mtr. max spi pole length 3.8 mtr
boats from 19 ft and beyond : max spi are 25 sq. mtr. max spi pole length 4.1 mm


These rules do actually coincide with the old rules at the hull lengths 16'5", 18 ft and 20 ft

So nothing REALLY changes in the handicap system, it is just that the rules are alot more simpler to understand and check for compliance (in addition to being more fair)

Wouter

Wouter.

You know full well that the SCHRS rules are being looked at at the moment. You also know I cannot comment until we have signoff from the ISAF.

You have made these points already. We were considering these points before you made them. I will report on our decision on this item and others when we have sign-off from the ISAF.

No need to continue to repeat the same thing over and over. I've told you more than once that we are looking at the issue of pole lengths.

Edited to add, this is waaaaaaay of topic, lets return to the 2007 UK travellers Trophy!

Thanks Geert,

I stand corrected... I should read my homework more carefully before starting to speak out loud <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

--
Valtteri

Sorry Scooby,

Was out of line here.

I should have remembered.

Wouter

Hi all,

maybe it is a Catrig thing but I am happy, with my 3m. pole <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />. No pole envy here <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />.

Is there any advantage for longer pole on catrigs?

Regards Gary

I Sail Cat rig with a Landy Spinnaker. A longer pole gives me a sheeting angle between the shrouds and front beam so whilst gybing the sheets only have the resistance around the fore stay. Previously with an Ullman Kite and shorter pole the kite blocks were fixed near the centre board casing and therefore there was more friction on the spi sheets around the shrouds. That was my main reason for lengthening my pole. I suppose I should really contact Landenberg to find out what the optimum angles and measurements are in this respect as I guess your kite was custom designed and manufactured to your needs.
As for making a difference to the boats speed I haven't got a clue, I would imagine the sheeting angle and luff tension are more critical than the distance of the clew from the mast foot (pole length).

Hi Gary
Getting back to the subject in hand what are your and your fellow sailors views on Discards? When you're entering Regattas in Oz whats the normal number of races etc.

Mainly in mark roundings when the other guys aren't giving you the space you need. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

My pole is a mere 3.25m and works fine with jib or cat rigged.

I tried several different "pole" lengths by moving the block at the tip. This was needed as the sailmaker made an error with my spinnaker making the foot too short. I went from 3.45 to as low as 2.75 mtr in front of the mainbeam, if I remember it right. I now have 3.25 mtr and have moved my sheeting block from the sidestays to the mainbeam. I found that below 3.20 mtr the spi would increasingly hang up on my forestay in cat rigged mode. It would want to move between the mast and forestay instead of between its luff and the forestay. It does so much more then when the jib is fitted. At 3.25 and longer the spi pretty much blows itself through the right gap and so I settled on that. At longer pole lengths the spi is noticeably easier to gybe. At least it is on my boat.

Wouter

Hi all,

We should propably start a new topic about spi pole length, so that this thread would stick to it's original topic. IMHO techinical talk always deserves it's own thread <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

I'll just go and start one...

--
Valtteri

Anyother issue with pole length is "helm," that is to say the longer the pole the greater the tendency for lee helm downwind.

Hi Mark,

most regattas work on minimum 4 races, no drops. 5 races plus, 1 drop. 7 races plus, 2 drops. I think <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />.

I like the idea of dropping races, &#it happens.

Regards Gary. <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />