Ardenfour
Active member
hi, can anyone advise what the relative tensions are on the standing rigging of a masthead sloop, with fwd and aft lowers please?
rigging tensions
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Vara
Active member
bluedragon
Active member
I'm trying to sort out the same issue on my Halcyon 27 at the moment. The Selden guide suggests 15% of wire break load as a dockside tension for cap shrouds and backstay(measured by extension of the wire). Elsewhere I've read that 10% is the correct starting figure for cruising yachts. Others will say it depends on the boat. On my Halcyon 27 I feel 15% is too high based on trials I've done. I'm going to try with 10%, then check-out what the leeward shroud is doing when sailing close hauled. You'll read that you can't overtighten rigging with hand tools. Frankly I think this is misleading...I easily got up to 15% of break load with greased terminals and could have gone way beyond this with no trouble. Maybe they mean you can't break the wire with hand tools...but you could break the boat I'd suggest!!
cjepearson
New member
I agree that it is important not to break the boat....I watched with morbid interest one day in Durban,RSA while someone demonstrated the efficiency of his back stay adjuster by twiddling this huge wheel. Next thing you know he has very considerable mast rake.....the foredeck parted company with the hull. It was an open 24ft sports boat, so no great suprise I suppose, but it gave us a shock, as we were in the next berth! I have been very tentative with rig tensions ever since.
PeteCooper
Well-known member
The relative tensions vary depending on the angles at which they are set relative to the mast i.e. the position of the chainplates. People seem to be getting worked up about rig tension just recently and really shouldn't be. It is easy to get a basic set up by getting the mast centered and straight from side to side then getting the prebend to match the luff of the main. Then tune the rig whilst sailing in about 12 to 15 knots of wind with full sail - a gps helps here. First set the rake by adjusting the forestay until the boat has the feel that you want. This would normally be slight weather helm. Then tighten the leeward shrouds to just remove the slack, tack and tighten the new leeward side by the same amount. Note the boat speed (hence the gps). Tighten the leeward shrouds by a half turn and tack. Note boat speed. If it has increased tighten the new leeward shrouds by a complete turn, tack and note speed. Continue until no increase in boat speed is noted, ensuring that each side is adjusted the same from the initial straight position.
Vara
Active member
If you do it like this a GPS will give you speed over ground,what you need is speed through the water which only a "Log" will give you.
I spose that if you are only looking for increases of speed over a short period then GPS might be OK.
Cut out as many variables as possible and go direct to Log reading.
I'm still trying to work through the angles and chain plate bit,but that doesn't sound quite right either.
Watch this space.
I spose that if you are only looking for increases of speed over a short period then GPS might be OK.
Cut out as many variables as possible and go direct to Log reading.
I'm still trying to work through the angles and chain plate bit,but that doesn't sound quite right either.
Watch this space.
Ardenfour
Active member
Thanks for all the replies. I posed the question, not from the point of view of mast adjustment, rather, is there a greater tension when sailing on the fwd or aft lowers, forestay, backstay etc. I realise this would depend on point of sailing, but my lower shrouds are different thickness, can't remember which way round. I have no chainplates fitted at present as they all need replaced and have been removed. I am curious as to how strong the new installation has to be, and the ratios of the tensions through the various attachment points to the hull.
William_H
Well-known member
Hi Halcyon the strength of the chain plates is of course critical. it is probably easiest to compare yours with similar boats. chain plates don't often fail. However the structure it is fastened to and the bolts used are all in the load circuit. For the side stays there is a circuit from the chain plate down to the keel then up to the other chain plate with of course the deck needing to be strong to hold the chain plates apart. Fortunately boat hulls don't often fail but they do get distorted by the rig stay loads. ( there is lovely old 30 ft wooden racing yachtg near me where you can clearly see the chain plates at the gunwhale have over the years distorted the gunwhale (shear) upwards at the chain plates.
The concept of tightening to 10% of max rated load of the wire presupposes that the rest of the structure in the circuit ie hull and mast is of a strength and stiffness comensurate with the wire size. So if oversized wire was used by some conservative previous owner then you could find the hull the weaker part and really over do it.
Now with your fore and aft intermediate stays. They obviously share the load of keeping the middle of the mast under the mast top and over the tabernacle in a way that would need much less power because they each pull in one direction of 4. So my opinion is to tighten up reasonably firm but in a way that keeps the mast straight both at the dock and when pressed under sail. the idea of taking up the slack on the leeward shroud seems ok but I woulddn't try to take out all slack. The load when hard pressed sailing is very high and I would not want to replicate that continually when on the mooring. In deed some locals here use a high field lever on the forestay of a fractional rig to completely unload the rig when they leave the boat. good luck with your rebuild. olewill PS I have to warn you many experts disagree with my idea that 10 or 15% is too much.
The concept of tightening to 10% of max rated load of the wire presupposes that the rest of the structure in the circuit ie hull and mast is of a strength and stiffness comensurate with the wire size. So if oversized wire was used by some conservative previous owner then you could find the hull the weaker part and really over do it.
Now with your fore and aft intermediate stays. They obviously share the load of keeping the middle of the mast under the mast top and over the tabernacle in a way that would need much less power because they each pull in one direction of 4. So my opinion is to tighten up reasonably firm but in a way that keeps the mast straight both at the dock and when pressed under sail. the idea of taking up the slack on the leeward shroud seems ok but I woulddn't try to take out all slack. The load when hard pressed sailing is very high and I would not want to replicate that continually when on the mooring. In deed some locals here use a high field lever on the forestay of a fractional rig to completely unload the rig when they leave the boat. good luck with your rebuild. olewill PS I have to warn you many experts disagree with my idea that 10 or 15% is too much.