I will be flying an asymmetrical spinnaker or cruising chute on my E29, and need advice on the best method of turning spinnaker sheets back to the winches from as far aft as possible. I dont think genoa blocks are the right solution. Garhauer is recommending foot blocks that can handle at least 4,000lbs SWL, and these would be mounted on the aft part of the foaming where the winches sit. Could also go with snatch blocks on the genoa track, but would need a custom track car made to handle same load. Which is best? Does the sheet angle from coaming level versus track level make a big difference? Thanks!
Where to turn that sheet lead
Until Seth or someone else checks in that knows what's what......
I would only caution you not to assume that an Asym. Sail or even a triradial automatically needs to be sheeted all the way aft.
I can recall receiving that same advice 30 years ago, and then over time finding that the sail would tell me where it wanted to be sheeted.
Even tho our present boat is a masthead rig and one might expect the chute to want to be sheeted way aft, it seems to fly best when the snatch block is up by the primary winch. Admittedly, having a slotted alum. toe rail gives me a lot of options for block placement.
So try the lead at different positions and see where the leach "breaks" and then decide what works best for your sail and boat combination.
OK, that wasn't even worth .01, but someone is bound to wander thru here with first hand info...
Cheers,
Loren
Until Seth or someone else checks in that knows what's what......
I would only caution you not to assume that an Asym. Sail or even a triradial automatically needs to be sheeted all the way aft.
I can recall receiving that same advice 30 years ago, and then over time finding that the sail would tell me where it wanted to be sheeted.
Even tho our present boat is a masthead rig and one might expect the chute to want to be sheeted way aft, it seems to fly best when the snatch block is up by the primary winch. Admittedly, having a slotted alum. toe rail gives me a lot of options for block placement.
So try the lead at different positions and see where the leach "breaks" and then decide what works best for your sail and boat combination.
OK, that wasn't even worth .01, but someone is bound to wander thru here with first hand info...
Cheers,
Loren
Bill Sanborn
Member III
On my E29 it doesn't help to have the spinnaker lead all of the way aft. The reason is that if it is too far aft it rides on the underside of the boom.
You might want to check this before drilling holes.
You might want to check this before drilling holes.
Garhauer makes a track fitting that is essentially a movable pad-eye:
http://garhauermarine.com/catalog_process.cfm?cid=77
Then all you need is a 4000 lb rated snatch block. I suspect this might be cheaper than a dedicated genoa track block and you can of course vemove the snatch block when not flying the spinnaker. Also, you can experiement with its position on the track, which you couldn't do with a foot block.
http://garhauermarine.com/catalog_process.cfm?cid=77
Then all you need is a 4000 lb rated snatch block. I suspect this might be cheaper than a dedicated genoa track block and you can of course vemove the snatch block when not flying the spinnaker. Also, you can experiement with its position on the track, which you couldn't do with a foot block.
I spoke to both Mark and Guido at Garhauer, and they were concerned about the SWL of the track car listed on their site - not designed for heavy loads. They did say they would be willing to fabricate a custom, beefier car.
It sounds like the foot blocks are not the way to go, and that I need a solution that is adjustable to be able to find the optimal sheeting angle for the spin sheets. Sounds like the custom cars and the snatch blocks are the way to go...
Thank you all for your insight. Much appreciated!
Gary Schroeder
Member II
How strong?
Some days I just don't catch on too fast. If I read their chart right, this rigging supplier recommends 3/8" Samson line with a Breaking Strength of 4,400 lbs. for spinnaker sheets on a 30' racer/cruiser. Their recommended SWL of 20% would be 880 lbs. on the sheet. Why would the block need a SWL of 4,000 lbs.?
A turning block at the stern would experience 2x880 if the line made a 180* turn, but a sheet block on the deck that causes a smaller turn (like say 45*) will experience a much smaller % of that load. What am I missing?
Samsonhttp://www.americanriggingsupply.com/index_files/Samson_MarineLine_Selection.pdf
Some days I just don't catch on too fast. If I read their chart right, this rigging supplier recommends 3/8" Samson line with a Breaking Strength of 4,400 lbs. for spinnaker sheets on a 30' racer/cruiser. Their recommended SWL of 20% would be 880 lbs. on the sheet. Why would the block need a SWL of 4,000 lbs.?
A turning block at the stern would experience 2x880 if the line made a 180* turn, but a sheet block on the deck that causes a smaller turn (like say 45*) will experience a much smaller % of that load. What am I missing?
Samsonhttp://www.americanriggingsupply.com/index_files/Samson_MarineLine_Selection.pdf
Gary-
I'm definitely a newbie when it comes to sail loads and the recommended hardware to handle those loads. I am throwing out the 4K Lb SWL because that is what the kind folks at Garhauer recommended to me when I gave them details of the A-spinnaker square footage I'll be flying, boat length, etc. Beyond that, I'm posing the same question here and hope others can provide their experience/advice (hey, I've already abandoned the foot blocks in favor of track car slides with snatch blocks based on arguments presented here). If placing equiment to handle 4K Lb SWL is overkill for my application, I am really interested in understanding why. I will be checking out the link you posted next! The learning process is, well, a process...
Thanks!
I'm definitely a newbie when it comes to sail loads and the recommended hardware to handle those loads. I am throwing out the 4K Lb SWL because that is what the kind folks at Garhauer recommended to me when I gave them details of the A-spinnaker square footage I'll be flying, boat length, etc. Beyond that, I'm posing the same question here and hope others can provide their experience/advice (hey, I've already abandoned the foot blocks in favor of track car slides with snatch blocks based on arguments presented here). If placing equiment to handle 4K Lb SWL is overkill for my application, I am really interested in understanding why. I will be checking out the link you posted next! The learning process is, well, a process...
Thanks!
Its not the block but the whole car
If you have a chance go to your a neighbors boat that is not in good shape. Sneakily slide any car (jib lead, spinaker etc) from its normal position and I will bet that you will find wear and gouges in the track itself. A much stronger car will keep its shape better distributing the load across all of the surface where it rides on the track causing less point loading. This will extend the life of the track itself.
If you have a chance go to your a neighbors boat that is not in good shape. Sneakily slide any car (jib lead, spinaker etc) from its normal position and I will bet that you will find wear and gouges in the track itself. A much stronger car will keep its shape better distributing the load across all of the surface where it rides on the track causing less point loading. This will extend the life of the track itself.
OK, so using load formula on the samson ropes link Gary provided, I am using 25knots as the the max windspeed (being a little conservative), and 700sq ft for the spin sail area (taken from the Ericson Owner's manual for standard rig). I get a load at the clew of 1,750 Lbs. If blocks turn the lines 90-degrees or more, wouldn't that load basically double, and wouldn't I want a block/car assembly rated for at least 3,500Lbs as the SWL? Their cruising spin sheet line recommendation of 3/8 SL I can understand, since any point on the line won't exceed the 1750 Lb tension load and the breaking load of that line is more than double that, but wouldn't the blocks/cars need a SWL at least double that load if there is any chance they turn the lines at a significant angle?
If the line turns 90 degrees the load on the block is around 1.5 times the load on the line. (theoretically square root of 2)
Also for Blocks and things with moving parts working load numbers usually refer to a load where the unit still works (Sheaves turn etc.). The breaking strength is higher.
One exception is Garhauer where the load numbers they give are the are set by the shackles that connect the blocks to the car or whatever. (if they are using third party shackles since their manufactured parts are much stronger)
I would also check with your sailmaker and make sure your spin is able to take 25 knots of wind
Also for Blocks and things with moving parts working load numbers usually refer to a load where the unit still works (Sheaves turn etc.). The breaking strength is higher.
One exception is Garhauer where the load numbers they give are the are set by the shackles that connect the blocks to the car or whatever. (if they are using third party shackles since their manufactured parts are much stronger)
I would also check with your sailmaker and make sure your spin is able to take 25 knots of wind
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