Leeward Shroud Slack Question

[Case]

When I sail upwind in my Sea Sprite 23, the leeward shrouds slacken considerably. I tighten them up constantly (within reason) but I think the hull may be too flexy for that. The shrouds start to be loose at about 10 knots windspeed, more so in whitecap conditions. It gets excessive at times. Interestingly, the mast never really moves, even in rough water. The shrouds are tight all round when the boat is not sailing.

I am considering stiffening the hull but sometimes its best to do nothing (if it ain't broke, don't fix it, you know). My Sea Sprite 23 is built with a full hull liner and from what I am seeing, it basically is sitting there, doing almost zip for stiffening the hull!

What is your experiences with the correct amount of leeward shroud slack?

- Case

[Hirilondë]

It may be because of stretching in the weather shroud(s) as well. I found the same on my Renegade the first time I stepped the mast and sailed her. I did eventually figure out how to tune things up so that the slack was very minimal, even in quite heavy winds to weather. Fiberglass boats can take much tighter settings than wooden can, but you aren't tuning a banjo either. They make a gauge for testing how tight a shroud is, you might want to get one. Having all of them near equal helps, especially opposite pairs.

[Tim]

It's stretch. Still, you don't want it excessive, but slackening of the lee shrouds is normal and you shouldn't try too hard to "fix" it.

Over-tensioned rigging causes a lot of problems. Avoid it. The rigging need not be drum tight to properly support and straighten your mast when tuned.

[Shark]

I wouldn't worry too much about the leeward shrouds being slack while sailing unless the condition is extreme. Perhaps you could contact some other Sea Sprite owners and find out how tight they set their rigging. Then buy or borrow a tension gauge, such as a Loos Tension Gauge, sized for your rigging, and do likewise. I don't know what your sailing experience is but some amount of slack in the leeward shrouds is normal. Indeed having your rig too tight can do more harm than good, especially if the mast is deck-stepped and has no compression post.

My upper leeward shroud is always slack when sailing to windward in any kind of a breeze and my lowers are very loose at all times to promote mast bend and facilitate sail adjustment but each type of boat is different.

[David VanDenburgh]

As I understand it, the most important issue is keeping the mast in column and preventing it from pumping. That means that leeward shrouds can be slack, but they should not be so slack that they move around enough to cycle, which fatigues the wire and can cause premature failure. As long as your mast stays in column on both tacks and doesn't pump excessively, I wouldn't be too concerned.

We go through this at the beginning of every season. Spring commissioning involves a dockside tune that places the mast in its correct position fore and aft and side to side. We use a Loos gauge to get the rig tensions balanced, then we head out for dynamic tuning under sail. That process involves checking mast tune on both tacks and, generally, taking up a bit of tension on the leeward shrouds to keep them from cycling and then tacking and doing the same on the opposite side, always double checking mast tune. After a sail in stiffer winds, we re-check the rig to make any necessary adjustments due to stretch.

[LazyGuy]

Case,

Since your boat has a liner, I assume you have a C.E.Ryder Sea Sprite. They are not known for deck problems but one thing to check could be deflection of the mast step. The older sprites, particularly the day sailors were notorious for deck problems. So while there is not a big chance that the mast step is a problem, it is an additional thing to check. There is a crown to the deck so it is not REAL easy to check for deflection particularly when you are on your ear with 15kts of wind but a straight edge can at least tell you that there is a concern. Also, when you are looking for deck deflection, take a look up at the jumper and ensure that the cross bar is still straight. I had a dent in the mast between the spreader and the jumper and found that it made a weak spot on one side so when the wind piped up on port tack, the upper portion of the mast twisted off to port. That was when I decided to replace the mast.

[Duncan]

Here's a "cut and paste" from a Cape Dory manual. There are a few tips I've found handy:

[Case]

Thanks all - I think I will do nothing for this year about reinforcing the hull.

I guess I will just have to crank up on the shrouds even more. The standing rigging was new in 2006 and it may have not been finished stretching out. When I have white cap conditions, the leeward shrouds flap around about 1-2 inches but the mast seems to be straight and has no problems whatsoever. 1-2 inches is a tad excessive to me, hence my questions...

Is it normal for the hull liner to basically sit there in the hull doing almost nothing for the hull structure? The hull liner is basically tabbed to the hull along the sole area. The hull liner was attached in other areas with a peanut butter resin mix which has since broken into little resinous bits. It was extremely brittle.

- Case

[LazyGuy]

Case,

You are correct about the hull liner. It does nothing for the boat except make the inside look nicer. Before hull liners. the bulkheads were "tabbed" to the hull. The tabs have been the Achilles heel of pre-liner boats.

[Rachel]

This is off the topic, but since you brought it up, I'll just say that I've always thought the tabbed bulkheads were one of the plusses of a "stick built" interior over a "liner" interior. I believe that the bond makes for a stronger structure with less shifting when pounding to weather. Of course if the tabs have come adrift, they should be repaired (that could be a sign of poor initial bonding or some serious impact).

That's not to say a "liner" boat is bad, necessarily, but there's certainly nothing wrong with a tabbed bulkhead either, in my opinion.

Rachel

[Tim]

Liners exist only to increase production efficiency, which leads to either lower consumer prices, higher profits for the builder, or some of both.

No one ever switched to liner-type construction because it was better. It's just quicker (and therefore less expensive), and when one is building production boats to very specific price points, as demanded by consumers and the market, this has proved to be an effective means of streamlining production.

These days, interior liners are frequently engineered to carry loads, but the earliest liners were just there to cover the raw laminates and served no structural function. That said, I am not intimately familiar with the construction of the Sea Sprite 23, with or without a liner, so these comments should be taken in the general sense intended.

[LazyGuy]

Tim and Rachel,

Point taken. There are advantages to tabbed bulkheads including increased flexibility for redoing interiors. A FYI about the Sea Sprite interiors is that the liner/old tabbed plywood interior were simply for furniture and while furniture can be used to increase rigidity I do not think it is required or needed on the Sprite.

[gone2ddogs]

And when your boat is holed below the waterline 1000 miles off shore. The lack of a liner to cut through to effect emergency repairs is probably a good thing.

JR