IRC Rating hits for Assymetrics and Bow Sprits

[Ceirwan]

I do a lot of short handed sailing quite often single handed, and am thinking that I'd probably increase my enjoyment of the boat a lot more by getting some kind of asymmetric and removable sprit, to make downwind sailing a bit more fun.

However I do race the boat as well, some I'm wondering how big an effect these things will have on my rating, and what I can do to minimise it. (Barring the obvious solution of just not using them when racing)

The current pole doesn't really extend past the bow at all, so a sprit will increase my STL for definite.
And there's also the selection of the sail, getting the best performance window without hitting the rating too hard.

The boat's an MGC27 so while she surfs well enough, she's not a planing design so I can't imagine too many scenarios when racing were tacking downwind would be quicker than just sailing deep with the symmetric.

Has anyone who's been through this process got any pointers?

 

[flaming]

I do a lot of short handed sailing quite often single handed, and am thinking that I'd probably increase my enjoyment of the boat a lot more by getting some kind of asymmetric and removable sprit, to make downwind sailing a bit more fun.

However I do race the boat as well, some I'm wondering how big an effect these things will have on my rating, and what I can do to minimise it. (Barring the obvious solution of just not using them when racing)

The current pole doesn't really extend past the bow at all, so a sprit will increase my STL for definite.
And there's also the selection of the sail, getting the best performance window without hitting the rating too hard.

The boat's an MGC27 so while she surfs well enough, she's not a planing design so I can't imagine too many scenarios when racing were tacking downwind would be quicker than just sailing deep with the symmetric.

Has anyone who's been through this process got any pointers?

Assuming that you want to add an A-sail to bridge a hole in your performance then I think the first step is correctly identifying the hole. Given that you say (and I'm happy to bet that you are right) that for your boat an S-sail is the fastest way downwind, then adding an A-sail to sail deep angles is not your hole. So maybe your hole is hotter angles in breeze, or a light airs hot angle A1.

What is often not fully understood about bowsprits is that the reason that they are long on boats that have only A-sails is that this is how to get such a boat downhill. If you are only looking for an A-sail to sail hotter angles then you don't actually need a great big bowsprit.

The conventional wisdom is to stick on the smallest fixed prod that you can whilst keeping the tack of the A-sail clear of all of your bow paraphernalia. This will increase your STL slightly, but hopefully not too much, and should enable you to set a really nice A-sail for hot angles. This also has the advantage of being a comparatively cheap option. You can also then increase the length of your regular pole to match your new STL with no further penalty and hopefully gain a bit more projection when running deep.

For example, here's two pics of sisterships. The first is setup for A-sail only, whilst the second has A-sails for reaching and light airs VMG, but symmetrical kites for normal running.

 

[Ingwe]

What Flaming has said is completely correct for a fully crewed setup. If however you want the convenience of being able to gybe the asymmetric short handed the thing to do is to have a second "short handed" IRC certificate which you have declared with only the bow sprit (you have to tick the box saying you will not carry a spinnaker pole else you get clobbered on STL) and asymmetric kites, doing this you would find that an A2 asymmetric which measures about 12 to 15 % bigger than your current symmetric flown off a pole about 1.2m longer than J will give you roughly the same IRC rating as your symmetric setup. If you do this you will end up slightly slower downwind in medium airs, but faster in light airs downwind and faster when reaching.

 

[flaming]

What Flaming has said is completely correct for a fully crewed setup. If however you want the convenience of being able to gybe the asymmetric short handed the thing to do is to have a second "short handed" IRC certificate which you have declared with only the bow sprit (you have to tick the box saying you will not carry a spinnaker pole else you get clobbered on STL) and asymmetric kites, doing this you would find that an A2 asymmetric which measures about 12 to 15 % bigger than your current symmetric flown off a pole about 1.2m longer than J will give you roughly the same IRC rating as your symmetric setup. If you do this you will end up slightly slower downwind in medium airs, but faster in light airs downwind and faster when reaching.

Yes, but then you are left with an A-sail setup that you cannot use fully crewed. I guess it just comes down to you priorities, both with what you're actually trying to achieve and how much money you're prepared to throw at it!
I did read the OP that the short handed sailing was not racing, and he was looking for a setup that would allow a bit of easy fun when in that mode, and to double up as a racing benefit.

 

[Ingwe]

Yes, but then you are left with an A-sail setup that you cannot use fully crewed. I guess it just comes down to you priorities, both with what you're actually trying to achieve and how much money you're prepared to throw at it!
I did read the OP that the short handed sailing was not racing, and he was looking for a setup that would allow a bit of easy fun when in that mode, and to double up as a racing benefit.

I know, things would be much simpler if IRC allowed you to declare the two types of spinnaker and pole separately and it would only need 2 extra numbers on the certificate.

 

[Ceirwan]

Some great responses, thanks.

Flaming is correct in that the main reason for it is when sailing short handed, at which point I'm usually not racing, or if I am then it will be a longer distance race that I can't get all the crew to commit for.
You're also correct that probably reaching and broad reaching are where I'm most looking to see the benefits.

She only carries a relatively small No3 genoa, upwind the setup works very well providing I have a little breeze, but anywhere past 90 degrees without the kite in light airs I just need more power.
Added to that there's a lot of shipping, lots of mud and sand banks so flying the symmetric spinnaker single handed can be really hard work.

I had imagined a setup on a furler that can be hoisted when required.

The picture of the second boat is what I had envisaged with regards to sprit length, something like the C-Sprit or the Trogear ones look ideal. I can't fit the gear until the end of the season so I've plenty of time to decide.

I guess the best thing to do would be to talk to my sail maker and see what they would recommend.

 

[Chris 249]

What Flaming has said is completely correct for a fully crewed setup. If however you want the convenience of being able to gybe the asymmetric short handed the thing to do is to have a second "short handed" IRC certificate which you have declared with only the bow sprit (you have to tick the box saying you will not carry a spinnaker pole else you get clobbered on STL) and asymmetric kites, doing this you would find that an A2 asymmetric which measures about 12 to 15 % bigger than your current symmetric flown off a pole about 1.2m longer than J will give you roughly the same IRC rating as your symmetric setup. If you do this you will end up slightly slower downwind in medium airs, but faster in light airs downwind and faster when reaching.

Can I butt in and just check whether the same numbers apply when fully crewed? That is, if I increase my spinnaker size by 10-15% and stick on a 1.2m long fixed centreline bowsprit/pole/dork/prodder and don't measure in a symmetrical kite, I will get roughly the same sort of rating as a standard boat with standard size assy kite? My boat is a J/36.

By the way, do you know the current treatment for assy sails set off normal conventional poles?

 

[Ingwe]

Can I butt in and just check whether the same numbers apply when fully crewed? That is, if I increase my spinnaker size by 10-15% and stick on a 1.2m long fixed centreline bowsprit/pole/dork/prodder and don't measure in a symmetrical kite, I will get roughly the same sort of rating as a standard boat with standard size assy kite? My boat is a J/36.

By the way, do you know the current treatment for assy sails set off normal conventional poles?

Yes roughly. I am basing this off the ratings for my current boat (sunfast 3200) where the symmetrical boats rate with a roughly 83sqm kite and the assy boats use a 93sqm kite and you end up with roughly similar ratings. The STL measurement will obviously increase with boat length and you would have to chat to your sail maker to find out what they thought would be optimal for you.

There is no treatment for assy sails off a conventional pole, they can be up to the same size as whatever you have declared as your max SPA for your symmetrical kite.

 

[Chris 249]

Great information - thanks very much.