Replacing main sheet on Irwin 37

[jimford2158]

Hi all, would anybody happen to know the correct size and length for the mainsail sheet on a Irwin 37 center cockpit. The one on the boat only lets the sail out to 45 degrees so I know it's too short. I'm also missing the boom vang but I have the specs on that, though I still need to get one :cry: . I can't find any other info on this, Thanks

 

[Joe]

Ease the boom out to your desired maximum position, measure from boom block to traveller, them multiply by the number for purchases.... plus what ever you'll need from traveller to winch to cockpit. It is much safer to measure your own than take the word of another... setups may vary for different boats.

 

[sailingdog]

It really depends on the length of the boom, the type of purchase, and where the mainsheet terminates on both ends. On a boat with a 12' boom, and a 6:1 main sheet, you'll want about 100' of mainsheet.

Basically, the calculations you'll want are:

End Boom Mainsheet Length
For 4:1 mainsheets = E x 5.6
For 6:1 mainsheets = E x 8.4

Mid Boom Mainsheet Length
For 4:1 mainsheets = E x 4.3
For 6:1 mainsheets = E x 5.7

Of course, if you use three blocks on the boom for the 6:1 mid-sheet main sheet setup, you'll need a longer line than if you use a single triple block on the boom.... etc...

Hi all, would anybody happen to know the correct size and length for the mainsail sheet on a Irwin 37 center cockpit. The one on the boat only lets the sail out to 45 degrees so I know it's too short. I'm also missing the boom vang but I have the specs on that, though I still need to get one :cry: . I can't find any other info on this, Thanks

 

[jimford2158]

Thanks, I let the boom out while docked and it hit a hard stop and the sheet was about 10 feet too short. It's only 3:1, I believe, one double and 2 singles, and it took 55 feet. I went with 3/8 since I don't plan on racing it. Going out in the Gulf tomorrow, hopefully before it storms. Thanks for the help.

 

[sailingdog]

If you have two blocks on the boom and a double on the traveler, you have a 4:1 main sheet more likely than a 3:1 main sheet. The simple way to tell which it, unless you have a dual-ratio mainsheet is to count the number of times the line goes between the boom and cockpit.

These are 4:1

This is a 6:1

Thanks, I let the boom out while docked and it hit a hard stop and the sheet was about 10 feet too short. It's only 3:1, I believe, one double and 2 singles, and it took 55 feet. I went with 3/8 since I don't plan on racing it. Going out in the Gulf tomorrow, hopefully before it storms. Thanks for the help.

 

[Ron20324]

Thread some sting or light (cheap) line the way you want it to run, let the boom out as far as it will go, then take the string out and measure it.

 

[Stu Jackson]

Ron's right, and add a few feet or more to make up for knots or splices and a stopper knot at the end.