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Old 16th September 2008, 05:45 PM   #1
robwootton
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Default Rig Economy

Hi Roger/Ellen,

I'm shortly about to get my first rig for my Carve 145 2005. To cope with all conditions i'm looking to end up with 3 sails initially to keep costs to a minimum. I've been looking to start with a Tushingham 6.5m T3 with a 460 75% freewave (would the 80% race be a little weak if I got caught in the shorebreak, or be fine?) and then go higher (8.0m T3) and lower (5.2m Rock?) as I save through next year. My question to you is that I want to get the biggest spread of sails for the minimum cost and therefore want to minimise on masts. So if I go initially for the 6.5m T3 on the 460 and then go for the 8.0m 4.95 luff T3 can I get away with the same mast with 35cm of extension, and if so what size extension do I require as I have heard there should definitley be a minimum amount left inside the mast (not sure how much). I can then buy only 1 more mast for a smaller sail (wave/high wind) when I'm good enough. Also could I get away with a 45% on a 400 mast (for the 5.2m ish) instead of 75%, as its much smaller with less moment forces than the 460(maybe the lighter mast shouldnt have so much effect on total feel if its shorter?). I am currently sailing mainly on a lake so the larger sails are required but definitely need the 6.5 or less for the sea when the wind gets up. So... I will soon have some rig money but unsure how to spend it, if you can help!

Best regards,
Rob

Last edited by robwootton; 16th September 2008 at 08:10 PM.
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Old 16th September 2008, 09:54 PM   #2
Roger
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Hi Rob,
Nice plan, but you may be overlooking something that could diminish the performance of
the sails you purchase.
Make sure that the masts you purchase have the correct MCS/IMCS bend characteristics for the sails you purchase.
I look at this a little differently.
Since masts now cost more than sails, and the weight difference between a low carbon mast (< 75% I consider low carbon) and a 75%-100% high carbon mast is quite significant, I'd look to get a really high carbon mast, as if you take care of it, it will last for many new sails (provided you buy sails that are compatible (IMCS bend characteristics) with your masts.
I don't think you will like the damage done to your Tush T'bird T-3 if you take it into the surf.
Wave sails have vinyl ester and fiberglass battens that are soft and flexy so they can withstand a pounding in the shorebreak.
Your T-Bird T-3 will have carbon rod and tube battens, which are easily broken even in small shorebreak.
So your plan to use a wave mast (so the mast won't break) when you go to the sea (with shorebreak) is OK, but if you wait to sail through the shorebreak until you have the skills to read the waves, make quick chicken jibes and get out through the breaking waves quickly and on the first try, your higher carbon mast and your Tush T-Bird T-3 will have a far better survival rate.
Small sails (wave or bump and jump oriented) and smaller 430/400/370 masts are often rated for use in the waves and they are built with materials and reinforceents to handle getting rolled in the surf.
But even small RDM wave rated masts do break frequently in larger surf.
So, wait until you have the skills to get out through the breaking waves on the first try, and know about chicken jibes in case you don't make it the first run, before taking even your smaller wave rated masts and sails into the surf.
Oh, and your Carve 145 is going to really be a handful in the surf as well.
If you plan to sail in an area with lots of shorebreak, I'd look for a smaller board to put your smaller sails on.
Hope this helps,
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Old 17th September 2008, 05:49 PM   #3
robwootton
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Hi Roger,

Thanks for the warning, I'll make sure I dont take out the larger sail if the surfs up and just save for a smaller wave sail later on, as I sail mainly at a lake at the moment. I know what you mean about the size of the board, though I'm not good enough to go out in waves at the moment, just trying to plan for the future.

As for the mast choice the 75% 460 is bang in IMCS range for the 6.5m T3 (at 25) and still in range but at the lower end for the 8.0m T3 (which is IMCS 25-29). Would I be able to use the 460 with an extension for the 8.0m (35cm required) and what sort of effect will this have on performance? Also How large an extension should I use and how much should be left in the mast? Could I damage the mast this way, it seems like a lot of extension?

Of course rideally I should get the exact appropriate mast for the sail or vice versa, but its good to know how these things can be stretched safetly to get good kit on a budget.

I'm hoping to end with 3 sails and 2 masts to cover most things whilst I'm progressing.

Many thanks,
Rob
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Old 17th September 2008, 09:57 PM   #4
Roger
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Hi Rob,
If you use a 460cm IMCS 24-26 mast in a sail that was designed to work on a 490 cm IMCS 28-30 mast, you will get the following issues and you will need to figure out how to "tune around" these issues to get anywhere near the design performance of the sail:
The top of the sail will fall away/twist off far too early in the downhauling process as the mast is not stiff enough up in the top to support the upper part of the sail as the tension begins to develop lower down in the sail.
You won't get the full draft in the lower parts of the sail because you cannot develop enough "perimeter tension" with the softer mast.
On an RAF sail like the T-bird T-3 this will result in alot of folded/bunched luff sleeve fabric in the middle 1/3 of the rig. If you get enough wind to fully open this up (the way it's supposed to work) you will have too much shape in the top of the sail due to the mast being less stiff up there and using significantly reduced downhaul.
You can sail the 8.0 with a long extension on a 460 cm IMCS 24-26 mast but you'll never get the full potential from the sail rigged that way.
As far as how much extension you need up inside the mast, that's pretty much established for you.
All of the longer extensions have about 45-48 cm of extension adjustment and then
another 13-14 cm (HPL=14 cm; Chinook= 13 cm; Streamlined= 13 cm) of full diameter (with no adjustment holes) above the top adjustment hole.
I've used extensions fully extended on occasion, but if you need to go more than 40 cm, a mast extender is usually the stronger way to go.
A mast extender is a fiberglass/carbon section of mast about 40 cm long that you can use with a short extension.
The top of the "extender" is machined to a ferrule configuration that fits snugly into the bottom of your mast.
Here's the specs. on the '08 Tush T-Bird T-3:
Size: 8.00 M2
Max. Luff length: 4.95m (495 cm)
Ideal mast IMCS rating: 29
Mast IMCS Range: 25-29
Boom length: 2.23
Battens: 7
Cams: 0
As you can see from the specs, you will need a 35 cm (mnimum as it may take a bit more or less to really get your sail tuned right) extension for your 460 cm mast.
If you are a light weight sailor, you may actually like the feel of the T-Bird T-3 with the softer mast and more twist at the top.
On a similar sail that I use, the 7.5 m2 Sailworks Retro, the recommended (and sail designed on) mast is a 460 cm IMCS 24-26m, but for heavier sailors, a 490 cm IMCS 28-30 is the recommended alternate mast.
So at only 35 cm of extension, I'm pretty sure you will be safe with a 45-48 cm (Tall) extension adjusted in the 32-38 cm range.
I'd suggest getting the 8.0 T-Bird and rigging it on your 460 cm IMCS 24-26 mast and then try to borrow a 490 cm IMCS 28-30 mast at some point to compare the differences.
Since Tushingham suggests quite a range on the IMCS rating (25-29) they may have designed in some compromise to make the T-3 to work better with both masts.
Hope this helps,
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Old 17th September 2008, 10:20 PM   #5
robwootton
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Thats great Roger, and very informative!

It looks like I can get away with using the 460 then, though not ideal. Buying more than one of the larger masts looks like it could have become expensive as there would be more relevance for the higher carbon content and thus .
I am surprised but glad I can use so much extension on the 460...I didnt want to wreck a new mast by experimenting without advice! I can see from your answer that the 8.0m sail will not function as well as it should without the 490, but I may have to put up with a compromise at the moment and I'm only 70kgs so may be ok.

Thanks again,
Rob
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