Vertical load from "high riding" headsail on rail

[Matt Papuga]

I own a 1977 Cat 30 and recently shredded my jib -- so I went out and bought a "close to fit" used one-- I unfortunatley have the original separate wire- not on the forestay-- old fashioned roller furling and could not find a replacement so I purchased a used hank on genoa for now. Anyway, the genoa foot "rides high" off the deck -- the luff is 40' the leech is 36' and the foot is 21'---- the leech should be about 39' or 40' for it to ride normally or what looks normal to me. Anyway, since the leech is short, the sheet has a large vertical component on it as it is tensioned and attaches directionally to the top rail via blocking-- I've tried to move the block forward and aft and it still has the large vertical component. I am an structural engineer by profession, but not a boat pro, but I feel as an engineer that the top rail is more of a shear attachement to get the sheet load to the winches on the horizontal than as a tension attachment. I can just see my top rail ripping and unzipping up vertically from the deck under high load from the high riding headsail. However, I love being able to see under the foot of the sail for visibility. Does anyone know anything about "high cut" or "high riding" headsails?

 

[Joe Barrett]

Buy a new jib!

That's the thing about buying used. it sorta fits, kinda fits but really doesn't fit. I suggest if price is the issue you look overseas to a loft like Rolly Tasker in Thailand. Great price and a jib that fits! By the way a high cut jib is called a Yankee, good in higher winds but not great in light air.

 

[Allen Schweitzer]

No added risk of failure due to your sail

Matt,If I understand your question, you're concerned about the force the jib sheet exerts on the block & deck hardware it's attached to. Specifically, you feel that the high cut of your current jib creates an "upward" force instead of the "horizontal" force a lower cut sail would give, AND you're afraid that this upward force will cause your block & deck hardware to fail.I wouldn't worry about it. If you have a high or a low cut jib, you will still have upward force on your block. Your decdk hardware is designed to handle these loads under most conditions.I, too, have a 1977 C-30 and our boats will heel excessively & dump wind to reduce force WAY before the deck hardware will pull out of the deck. It sounds like your dimensions work out to be about a 140% or a 150% sail. If you're still worried about failure, then don't use your boat in winds over 15 to 20 knots. With winds that high you'll want to use a smaller headsail.For winds below 15 knots, I think you should keep the sail you have & enjoy it. Our C-30's LOVE a large headsail with a steady breeze.I hope this helps!Allen Schweitzers/v DrambuieC-30 Hull# 632

 

[John Visser]

Clarification?

If you don't mind Matt, just a couple of quick questions:1. what is the "top rail" you refer to? Is it a "T"-section toe rail?2. What do you mean by shear and tension loads on the top rail? As you know, the load is applied directly in the direction of the sheet leading towards and away from the block; so, even if the angle from hte deck to line was as small as 15 degrees, you'd still have 30% of the load as the tension component. My point is that there is always a large tension component.Comment: with the clew so high, I'd be most concerned that I coldn't get the sail trimmed properly for all conditions. jv