What do you think would be the best purchase? I want to play the main sheet on our 6000 lb boat with188 sqft main with a 10-foot boom. One attachment point is 2 feet from the end, and the other center mounted in the cockpit. I'm hoping for low effort for ease of operation and less grunt.
Play the sheet
- Thread starter Quoddy
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Quoddy...
I would thing that the standard 4 to 1 purchase of the mainsheet blocks should be sufficient. Use smaller higher strength line as the mainsheet if easier/quicker response is needed over what was supplied.
Your best improvement would be to install a traveler across the cockpit sole and work the traveler instead of the sheet when a puff gets too strong. (I believe the starboard seat has a lid to the aft cabin ventilation port and storage bin that would preclude setting up a cross-ship traveler at the seat level as seen on some new boats). It also tends to cut the cockpit in half and limit fast movement fore-aft if needed). On the sole it could be a toe catcher however.
The traveler would let you create twist at the top of the mainsail, enabling you to spill wind and keep the boat more upright. Three to one on the traveler lines should be sufficient, but 4 to 1 could be rigged as well to make it easier on the trimmer.
I would thing that the standard 4 to 1 purchase of the mainsheet blocks should be sufficient. Use smaller higher strength line as the mainsheet if easier/quicker response is needed over what was supplied.
Your best improvement would be to install a traveler across the cockpit sole and work the traveler instead of the sheet when a puff gets too strong. (I believe the starboard seat has a lid to the aft cabin ventilation port and storage bin that would preclude setting up a cross-ship traveler at the seat level as seen on some new boats). It also tends to cut the cockpit in half and limit fast movement fore-aft if needed). On the sole it could be a toe catcher however.
The traveler would let you create twist at the top of the mainsail, enabling you to spill wind and keep the boat more upright. Three to one on the traveler lines should be sufficient, but 4 to 1 could be rigged as well to make it easier on the trimmer.
Gee, I would think a little more than 4:1.
I assume you have a vang.
A Hobie Cat has 6:1, weighs 650# loaded, and has boom-end sheeting. Try that, and do not over size the line; some do that for better grip, but then it doesn't run as well.
I assume you have a vang.
4:1
My Mirage 27 had a 4:1 mainsheet which was plenty of mechanical advantage. A traveller will make all the difference. You would probably want the small or midsize harken traveller. I do a fair amount of racing. The traveller and vang are what you generally are going to play in the puffs and lulls.
My Mirage 27 had a 4:1 mainsheet which was plenty of mechanical advantage. A traveller will make all the difference. You would probably want the small or midsize harken traveller. I do a fair amount of racing. The traveller and vang are what you generally are going to play in the puffs and lulls.
Quoddy, purchase power makes a difference depending on if a boat has end, 3/4 or mid boom sheeting. Mid boom sheeting requires more purchase power than end boom sheeting if the force applied to the sheet is to be equal.
The main sail on my C&C 29 is very similar in size with an area of 177 sq. ft. It came from the factory with a 5:1 purchase mainsheet and is a 3/4 boom setup. With the 3/4 boom arrangement the weighted main sail area is 232 square feet. I found that this setup was underpowered in winds over 20 knots true. My biggest concern was trying to dump the sheet when it was highly loaded. The cam cleat was so highly loaded that you had to stand on the sheet to release it from the cam. Some owners upped the purchase to 6:1 and are happy with ease of adjustment. The problem now is that they have a lot of sheet to deal with in the cockpit. In light air, there is too much friction and easing the sheet doesn't always work without a crew member pushing on the boom to help it along. I fitted my boat with a coarse trim/fine trim setup. The coarse trim is 4:! and the fine trim is 16:1. I can quickly coarse trim or ease the sheet with the 4:1 purchase while not having lots of extra sheet in the cockpit. When it gets difficult to trim the coarse trim sheet I use the fine trim 16:1 sheet for final adjustments and for playing the sheet if necessary. It's very easy to make adjustments and release the sheet from the cam cleat even when the sheet is highly loaded.
The main sail on my C&C 29 is very similar in size with an area of 177 sq. ft. It came from the factory with a 5:1 purchase mainsheet and is a 3/4 boom setup. With the 3/4 boom arrangement the weighted main sail area is 232 square feet. I found that this setup was underpowered in winds over 20 knots true. My biggest concern was trying to dump the sheet when it was highly loaded. The cam cleat was so highly loaded that you had to stand on the sheet to release it from the cam. Some owners upped the purchase to 6:1 and are happy with ease of adjustment. The problem now is that they have a lot of sheet to deal with in the cockpit. In light air, there is too much friction and easing the sheet doesn't always work without a crew member pushing on the boom to help it along. I fitted my boat with a coarse trim/fine trim setup. The coarse trim is 4:! and the fine trim is 16:1. I can quickly coarse trim or ease the sheet with the 4:1 purchase while not having lots of extra sheet in the cockpit. When it gets difficult to trim the coarse trim sheet I use the fine trim 16:1 sheet for final adjustments and for playing the sheet if necessary. It's very easy to make adjustments and release the sheet from the cam cleat even when the sheet is highly loaded.
Sheet change
Thanks for all the comments and possible solutions. I'm looking at 6/1 or two speed and were the attachment points might go for it, cockpit space is limited.
Thanks for all the comments and possible solutions. I'm looking at 6/1 or two speed and were the attachment points might go for it, cockpit space is limited.
Look at your blocks as well. Some of the factory supplied hardware is marginal in that there is considerable friction which increases effort. Look at Harken carbos or something similar. 4:1 seems like it ought to be sufficient, 6:1 is going to put a lot more line in the cockpit.
DougM's comment is spot-on. I replaced the original Shaefer main sheet set-up with a larger ball bearing set-up from Garhauer with the same purchase. The reduction in effort is substantial. You might be able to get away with making just that change.
There's some good info above. The more the MA the more line you will be feeding. If your attachment point is the end of the boom, that will give you more power as it creates a longer righting arm (as offered before), but you have to consider the bottom end and where that attaches. If it attaches to a traveler, then you have to consider side load at the car, if you start moving your boom attachment point around. Some travelers are designed to take side load as the car bearings are distributed in a design that will enable it to roll easily and some cars aren't so that it loads up and binds rendering it not good for effective movement.
And, in a gust, you should dump the traveler first, before the sheet for quick mainsail depowering. You can also dump the vang, which will depower the top of the sail due to the added twist.
And, in a gust, you should dump the traveler first, before the sheet for quick mainsail depowering. You can also dump the vang, which will depower the top of the sail due to the added twist.
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