Tensioning shrouds without a Loos gauge

[Paul Moir]

Is it at all possible? I've been able to get the tension even between the shrouds very effectively by sighting up the mast, and the inner/outer tension ratio by sighting up the mast while sailing. But I've noticed they go completely slack when enough backstay is put on so I think I'm not running enough tension. I know I'm supposed to be running about 400lbs on the outers and 200 on the inners, but I really have no way of measuring.<br /><br />Any suggestions? Anyone heard of a home-made loos gauge?<br /><br />Thanks for any thoughts! All this stuff is new to me.

 

[tommays]

Re: Tensioning shrouds without a Loos gauge

paul<br /><br />i dont see how you can get it right what size wire ?<br /><br />because 400 is low even on 3/16 the min on a B guage is 10=240/15=320/20=440<br /><br />i am looking closer and the min on the B is realy about 20 on the top scale<br /><br />i run a GOOD tape measure up my most centered halyard and get the mast really centered between the chain plates after that you can tighten them evenly <br /><br />

<br /><br /><br />tommays

 

[Paul Moir]

Re: Tensioning shrouds without a Loos gauge

Yeah, I've got the mast centred properly. The main halyard is wire and I carefully measured from it to the chainplates. I'm confident it's correct to a 1/16". A little error here makes for a lot because the boat isn't beamy.<br />I think the outers are 7/32 and the lowers are 1/8". I'm not sure though so I'll check it out. Another tuning guide suggests 35 (outer) and 6 (lowers) as a starting point, if that's any help.<br />So I suppose that suggests I need two gauges then?<br /><br />Thanks for the help!

 

[tommays]

Re: Tensioning shrouds without a Loos gauge

91-Model A*Cable sizes: 3/23", 1/8", and 5/32" <br /><br />90-Model B*Cable sizes: 3/16", 7/32", 1/4" and 9/32"<br /><br />35 on 7/32 is 1000 pounds you getting pretty tight i dont think i would want to wing that<br /><br />what kind of boat is it i really never gave it much thought on my 14 and 18 ft boats the masts had no shapeing <br /><br /> i only got into it on the J-24 because the loads were so high and you could shape the mast so much to tune for wind conditions<br /><br />whats getting slack ? your never going to keep the leeward side tight there going to be slack<br /><br />it can be unnerving when you see the rod riging floping around on a 40 ft boat <br /><br />tommays

 

[Paul Moir]

Re: Tensioning shrouds without a Loos gauge

Oh, sorry about that! This is for my brother's Shark 24. You can get a good idea of the standing rig from this picture:<br />Click<br /><br />The outers only go up to the jumper spreader. The inners go to just below the spreaders. The jumpers go from just above the spreaders to the top of the mast. The beam is just over 6' which is why I think they went with this unusual arrangement.<br /><br />So it's perfectly normal to see the leeward lines go slack? The other thing was both outers went slack (with no sail up) when the backstay was applied. The chain plates are aft of the mast step.<br /><br />I think I will need to get those wire sizes before going much further here. Those are really just guesses from memory. I'll try to get out with a micrometer tomorrow. We've got a ocean race next weekend and I'd like to be at least a little confident about having the rigging close to right.

 

[tommays]

Re: Tensioning shrouds without a Loos gauge

thats a unusuall setup but i looked and its a 40 year old class i like it when they just keep on sailing<br /><br />the leeward lines go slack on every boat <br /><br />the back stay pressure affecting the outters i dont no on a j the mast bends insanely you can flatten the main compleaty<br /><br />i would just get them at the basic correct settings <br /><br /> i found over the years that the CORRECT SETTING often changed to what the fast guy was useing even it was not really to safe <br /><br />a really lose head stay became correct when kenney reed won a nationals that way even if it let the mast flop around in a stupid way <br /><br />i am going boating boating for a week on lake george have FUN on the race <br /><br /><br />tommays

 

[BillP]

Re: Tensioning shrouds without a Loos gauge

Paul,<br />Forget measuring tension and site the mast when sailing on a hard beat in heavy winds. Tighten just enough to keep the mast straight and nothing more. Headsails are the only place you need tight stays and leaving them tight enough to keep all slack out when sailing is tough on the rig. The wire stretches too. If you are a racing nut then put a hyd backstay adjuster and pump it up to xxxxx psi when needed for each particular headsail...then let the psi off for normal sailing. <br /><br />Be careful with jumpers because overtightening them can tension the mast and make it bend easier. It bends aft just behind them and at the worst times...lowers won't take care of that problem.

 

[Paul Moir]

Re: Tensioning shrouds without a Loos gauge

I knew I shouldn't have replied 'til I checked:<br />Outers: 5/32<br />Inners: 1/8<br />Forestay: 1/8<br />Backstay: 3/32<br />So if there was a gauge to buy, that would be Model A I take it?<br /><br />Sighting the mast has been how I've been setting up the rig so far, and it's served me well (I think). But since I'm so short on experience I really wanted to know if I was in the right ballpark. I will pay particulair attention to the area covered by the jumpers next time we're out in the proper conditions. Should I be sighting them during a spinnaker run? It's the largest foresail we carry now, having abandoned the genoa in favor of a larger, modern main (and a lower handicap naturally).<br />Also, the bend I should be looking for - is that at where the jumper shrouds attach to the mast, or where the jumper 'struts' come in to it?<br /><br />We're not serious enough to warrant a hydraulic backstay adjuster (yet!) but we'll experiment some with our arm calibrated pulley system there. I suspect we've been using the backstay incorrectly at times putting far too much tension on.<br /><br />We had a great day running last week, but unfortunately the winds were relatively light and the sea calmed as the afternoon ran on. I'm sitting atop the (not quite completed and unpainted) companionway hatch cover BillP helped me out with:<br />

<br />I hope tommays had the same nice weather on Lake George! Thanks again for the great advice, I'm learning more here than I could have hoped for!

 

[tommays]

Re: Tensioning shrouds without a Loos gauge

nice shot paul <br /><br />the weather on lake george was perfect only about 5 hours of rain the whole week <br /><br />i think the local sailors can help you better with this but <br /><br />the basic setup of the mast needs to fit the shape of the main as the sailmaker cut it to make the best air flow and power <br /><br />any backstay tension should start to put more bend in the mast which is going to flatten the main and REMOVE power from the main as the wind becomes to strong<br /><br />i cant see a boat that size needing anything hyd the J-24 has a simple pulley system backstay with lines that can be reached on eather tack by the helmsman allowing him to quickely adjust the main <br /><br />your comments about the sails are intresting because on the J the 150 gen was the most inportant upwind sail and people would flog the main before changeing down to the 100 <br /><br /><br />tommays

 

[tommays]

Re: Tensioning shrouds without a Loos gauge

 

[BillP]

Re: Tensioning shrouds without a Loos gauge

The idea is to keep the loaded wires straight and any more tension is not necessary. Backstay adjusters can shape sails on boats with flexi masts and/or used to tension headstays. The boats I've sailed on used hyd backstay adjusters only to take sag out of the headstay...but none of those boats had spindly masts either, including a Lindenberg 26 (a decade later than Sharks). They used downhalls, outhalls, leechlines, etc to adjust the mainsail. <br /><br />I think tommays gave good advice. Check you local race guys to see how to tweak you particular rig. Sharks have been 35+ years and there should be plenty of info available. It's an "old school" rig compared to today's racers so take that into consideration. Just don't tighten your rigging enough to make it strum like a banjo...otherwise it will slowly pull your boat apart over time.

 

[Paul Moir]

Re: Tensioning shrouds without a Loos gauge

Well, this is probably the definition of a spindely mast. Since the forstay only runs up part way, the backstay really shapes the main. I'm glad to hear my gut instinct to leave the lines a little to the loose side isn't catastrophic. All I could picture was driving the mast down through the deckhouse. <br />The club we're at has no Sharks, nor any boats as small as us racing anyway. Since I started this thread I've found a couple Shark guides I didn't know about though. But our sails are so different it's impossible to draw direct comparisons.<br />The main is a kevlar reinforced, fully battened and larger than the original main:<br />

<br />The principal forsail is the 110% jib. We have a second one made of spinnaker cloth with shoe-string sheets for very light air. Also there are the spinnakers. The reason for two is one is very old, full of holes and we've been expecting it to tear. It hasn't yet and it seems to perform better than the new one.<br />We have good mainsail controls - internal & on the fly adjustable outhaul, backstay adjustable from either side like the J-24, leachlines, vang, etc. We don't bother rigging the cunningham since it's pretty well useless with that sail (little to no streach, and impossible to adjust when it's powered anyway).<br />The jib is new, and a sail track was fitted to the forestay to accomodate this (on the advice of the sail maker). So the old genoa doesn't fit anymore since it used rings. The reason for the radical changes was that the previous owner was finding himself frequently badly overpowered and never seemed to be able to point very well. The new sails corrected both these problems very well.<br />Since then, my brother bought the boat and eventually changed clubs. Although the new club is much nicer than the old, it is located far further inland than the old one. So we're seeing lighter winds. Although the ultra-light jib functions very well in little wind and we make time on just about everyone with it, we're finding ourselves hopeless in 5-~15 knots. Anything above that we do well with.<br />So I think I'll try getting a track fitted to the genoa and experiment a bit. But I think there's a strong possibility we'll just have to recognise that the boat doesn't perform well in boring wind!

 

[BillP]

Re: Tensioning shrouds without a Loos gauge

You may need new sails. I put a new suit on a 29' sailboat and the difference was amazing. I even swapped them back and forth on the same day to record differences. Major performace gain from the new ones...new and old were the same sailmaker and same cut.

 

[Paul Moir]

Re: Tensioning shrouds without a Loos gauge

I should have pointed out, all of the sails except the (unused) genoa and one of the spinnakers are only 3 or four years old. The main looks funny due to the kevlar and carbon reinforcements & mylar.<br />Or is that getting on in years for a sail?