Bowsprit length

[harstonwood]

Hi all
Am just making a modification to the bowsprit arrangements on out boat
It's a selden one, and using their data, I could project it 1 m beyond the forwards attachment point, giving 1.2 m from the forestay. I may need to beef up the anchor roller and tie it into the stemhead (sprit attached to anchor roller)

So any thoughts on a sensible length? More the better? Less? Flying a hybrid cruising/asymmetric chute currently, off a top down furler

Thanks

 

[flaming]

Hi all
Am just making a modification to the bowsprit arrangements on out boat
It's a selden one, and using their data, I could project it 1 m beyond the forwards attachment point, giving 1.2 m from the forestay. I may need to beef up the anchor roller and tie it into the stemhead (sprit attached to anchor roller)

So any thoughts on a sensible length? More the better? Less? Flying a hybrid cruising/asymmetric chute currently, off a top down furler

Thanks

Depends...

What are you trying to achieve? Is this for a sail that you will use for all offwind sailing, or just to reach with? Do you also have a symetrical kite? Are you looking for just best performance, or taking rating effects into account? How are you planning to gybe the sail? Do you plan on having a bobstay, or just using the strength of the pole itself? All factors that will influence the size of pole you want!

 

[Judders]

SWMBO said I shouldn't worry about size.

 

[mrming]

Practicalities aside - longer is better:

More separation from the mainsail = less blanketing
Easier to gybe "inside" (in the gap between the a-sail luff and the forestay)
Makes room for a bigger sail

You see a lot of short, stubby bowsprits on IRC race boats, not because they are good, but because the rule counts a bowsprit as an oversize spin pole and that's pretty heavily penalised. Many boats compromise with a pole slightly over J, and a bowsprit that sticks out by the same amount.

 

[flaming]

Practicalities aside - longer is better:

More separation from the mainsail = less blanketing
Easier to gybe "inside" (in the gap between the a-sail luff and the forestay)
Makes room for a bigger sail

You see a lot of short, stubby bowsprits on IRC race boats, not because they are good, but because the rule counts a bowsprit as an oversize spin pole and that's pretty heavily penalised. Many boats compromise with a pole slightly over J, and a bowsprit that sticks out by the same amount.

Agree with all that IF the pole is intended to cover all angles from 90 to 180. (Though obviously 150-180 will be VMG running and gybing angles)

However, if the purpose is purely to have a reaching kite, and running will be a symmetrical kite, then going long on the pole is of limited advantage, as you often don't actually want such a big sail to carry on hot angles, blanketing is less with hot angles anyway, and the loads are a lot higher, so the beefiness of a pole can get silly as it gets long. There's a reason why the Pole that sticks out the front of a J109 is a lot bigger, thicker and heavier than the pole on a similar sized symmetrical boat.

 

[mrming]

Agree with all that IF the pole is intended to cover all angles from 90 to 180. (Though obviously 150-180 will be VMG running and gybing angles)

However, if the purpose is purely to have a reaching kite, and running will be a symmetrical kite, then going long on the pole is of limited advantage, as you often don't actually want such a big sail to carry on hot angles, blanketing is less with hot angles anyway, and the loads are a lot higher, so the beefiness of a pole can get silly as it gets long. There's a reason why the Pole that sticks out the front of a J109 is a lot bigger, thicker and heavier than the pole on a similar sized symmetrical boat.

Yep I've learned the hard way that an a-sail on a boat designed for a sym kite is a specialist tool at best. I've now taken the bowsprit and pretty large a-sail off our rating completely.

 

[harstonwood]

Depends...

What are you trying to achieve? Is this for a sail that you will use for all offwind sailing, or just to reach with? Do you also have a symetrical kite? Are you looking for just best performance, or taking rating effects into account? How are you planning to gybe the sail? Do you plan on having a bobstay, or just using the strength of the pole itself? All factors that will influence the size of pole you want!

Thanks
It's for reaching in light winds, but would like to use it down to 120-150 degrees perhaps. We are under crewed to fly a spinnaker with our pole, but find the chute on our top down furler fairly straightforward to use on the bowsprit. I need to fix the length when we declare it for our rating., hence need to sort the length. We gybe it through the gap.

Last years we sailed white sails class, but thought I might put the sprit/chute on our rating as we can still choose to enter white sails and use that rating. If we enter a race or series of races in the white sails class's, I guess we would not be able to have the chute onboard? Still trying to work out our options and plans for next year
Always appreciate your advice flaming.

 

[flaming]

If you intend to go downwind with it, then mount the biggest pole you can. Usually worth the rating hit, though worth saying that if what you are referring to as a "chute" is actually a cruising chute then you will struggle to go deep downwind. The J109s etc only manage it by having a kite with ridiculously large shoulders and using the crew weight to heel the boat far to windward to make it rotate. Quite impressive when done well, but (in my opinion) bloody stupid to have to hike a boat as hard downwind as you do upwind in 10 knots of breeze. I quickly learnt that kite trimmer is the job to have on that boat, only one who gets a break from hiking!
Also worth going long if you're gybing through the gap (I assume you mean between the pole/ luff of chute and the forestay...!) as the more space there the better.

However... I feel you should experiment - as I feel that the crossover from when it's better to go downwind goosewinged with the jib, as opposed to with the chute, will be surprisingly low on the wind scale. For 109s it's about 25 knots, for you I expect better VMG downwind by pointing at the mark goosewinged with a jib might be as low as 12-15 knots.
Also worth checking your local rules on goosewinging asymmetric kites, some places / class rules outlaw it. If not you could try that for medium winds, but it's very hard work unless the sea is mirror flat - and if it is you'll probably be faster sailing angles.

But if most of your racing is round the cans as opposed to ww/lw then the chute will be a useful sail reaching in light/moderate winds. And lets face it, almost always more fun!

 

[harstonwood]

Thanks Flaming....just the job, and your 12-15kts numbers seem spot on.
Will put it on the rating and try it out, and see how deep we can go. We intend doing some white sails racing anyway, so will practice with the chute and see how we get on, and compare it to goosewinging etc
It is a cruising chute but the sail maker claims is similar to a j109 style assymetric

Yes did some racing on a J109 this autumn and yes we did lots of time on the rail......did the trick though!

Thanks again

 

[H4B]

Thanks
It's for reaching in light winds, but would like to use it down to 120-150 degrees perhaps. We are under crewed to fly a spinnaker with our pole, but find the chute on our top down furler fairly straightforward to use on the bowsprit. I need to fix the length when we declare it for our rating., hence need to sort the length. We gybe it through the gap.

Last years we sailed white sails class, but thought I might put the sprit/chute on our rating as we can still choose to enter white sails and use that rating. If we enter a race or series of races in the white sails class's, I guess we would not be able to have the chute onboard? Still trying to work out our options and plans for next year
Always appreciate your advice flaming.

Is the boat IRC rated ? .

 

[harstonwood]

Is the boat IRC rated ? .

Yes
I have to decide the length, before I install and add to rating changes for next year

 

[Ingwe]

Have just re-read your original post and realised your using a top down furler - in which case the length of the pole may largely be determined by how far you can reach out from the front of the boat safely to attach the furler to the end of the pole - it is not easy to use a furler that is just attached on using a tack line as it tends to let the base spin too easily and makes furling / unfirling a lot more difficult. So you need to either be able to reach the end of the pole when extended or have a very easy way of bringing the pole back in to un-clip the furler.

 

[harstonwood]

Have just re-read your original post and realised your using a top down furler - in which case the length of the pole may largely be determined by how far you can reach out from the front of the boat safely to attach the furler to the end of the pole - it is not easy to use a furler that is just attached on using a tack line as it tends to let the base spin too easily and makes furling / unfirling a lot more difficult. So you need to either be able to reach the end of the pole when extended or have a very easy way of bringing the pole back in to un-clip the furler.

Hi
I can pull the pole back into the boat to attach the furling drum before hoisting.
I'm thinking about about 750mm in front of its bow bracket, giving approach a metre from the forestay

 

[H4B]

Yes
I have to decide the length, before I install and add to rating changes for next year

Ok so sounds a similar conundrum that I had a couple years ago when fitting a selden kit to my Westerly Fulmar. I settle for. 1.1 m projection for deeper AWA but fitted a second anchor point giving 550mm projection for reaching and higher loads when flying flatter cut A2. There is a rating penalty ( equates to .001 per 300mm ) but you have to balance , with considerations of crew skill and I know that with limited crew have no hesitation in launching the A4 whereas I would be more cautious with a Symmetrical. For our sort of racing its transformed it and greatly increased crew satisfaction and has proved very successful as far as results go.

 

[harstonwood]

Ok so sounds a similar conundrum that I had a couple years ago when fitting a selden kit to my Westerly Fulmar. I settle for. 1.1 m projection for deeper AWA but fitted a second anchor point giving 550mm projection for reaching and higher loads when flying flatter cut A2. There is a rating penalty ( equates to .001 per 300mm ) but you have to balance , with considerations of crew skill and I know that with limited crew have no hesitation in launching the A4 whereas I would be more cautious with a Symmetrical. For our sort of racing its transformed it and greatly increased crew satisfaction and has proved very successful as far as results go.

Thanks for that .....useful
Yes I intend having adjustable lengths to a max of about 1m