H18 shroud tension

what would be the correct tension (or play) on the mast shroulds

tight as you can, hang on the trap wire and pin it... then go up one hole.

adjust from there however you like.

mast rake ([b]or lack of actually[/b]) is probably more important than shroud tension.

I have come across more specific recommendations over the years, but they all boil down to " the harder she blows the tighter she goes". But like the previous poster, I also mostly just put on a hiking bucket and hang on a trap wire to tension my shrouds for daysailing. note: You must do this before you tension your jib halyard or you will have a mess on your hands.
If you are playing in any kind of waves at all, you need to be sure to pull all the slop out of your rig, and bigger waves that are exerting heavier loads on your rig, will require correspondingly greater tension to keep this slop from occuring. You just cannot allow your mast to bang back and forth, EVER. This slop is usually more evident when running off the wind, but can express itself upwind too. If you let this banging occur it will soon work harden the metal in your shrouds and they will fail quite prematurely. If you are sailing on inland lakes and the water is relatively flat the mast bang conditon is less of a concern, but even there any slack in your shrouds translates into slack in your forestay. The forestay always needs to be as straight as possible because it is the leading attack point for your whole sail system. If you are asking this kind of question, I'd be willing to bet you haven't come across a copy of Phil Berman's Hobie 18 manual...it will answer a whole bunch of questions you haven't even thought of yet.

Yes... mess=damage to the jib luff.

Only tension the jib luff (halyard / downhaul) when the rig / forestay is tight. If you tension with a loose rig, you can over come the forestay tension... then when you tighten the rig, the forestay goes tight... the luff gets stretched too much. You can tear out grommets or rip the sail or maybe just stretch it and ruin the luff shape.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Yes, I could have been more specific...mess is a terribly ambiguous term to use. The jib halyard line and cable are only meant to be strong enough to hold the needed uphaul on the jib sail. If you tighten that small halyard cable and line system, and then go back and use the boom and mainsheet to tighten your shrouds, you will end up transferrring the load meant for the forestay onto that halyard system!
If you don't tear sails or break the jib halyard as Matt said , you will surely stretch that jib halyard cable, and when you do it will coil up like a pigtail when the tension is relieved. This makes it very unmanageable, and you will soon choose to replace it, instead of fighting with it on that upper pulley, every time you rig.
Conversely the same stretching can occur to people who don't run sufficient shoud tension in the first place, because the loads of the sails can also be transferred to the jib halyard, if it is ever tighter than the forestay.
Oh, a postscript on the Phil Berman manual...if you are new to the 18 please don't think you need to make all those specific adjustments on your boat every time you go out to daysail. But his book is great winter reading for people with no sailing experience on the 18.
That being said, there is no amount of rigging adjustment that can take the place of good tactics and time on the water....so get your boat close and go sail...don't sit around on the beach measuring and sanding. Those are things you do in the OFF season.

about the jib tension.... i don't recall who or where I picked this up, so hard to give the credit where it is due... anyway...

set your mast rake and shroud tension.
put up your mainsail and hookup the mainsheet & blocks.
raise the jib and tension loosely.
bring the mainsheet to the front of the boat and sheet in hard, cleat it.
then tighten up and snug the jib
then loosen the mainsheet.

your jib luff tension is set.
if you keep the boat mast up and jib furled, remember to loosen the tension when done sailing for the day.

sheet in, hike out -Rob

Regarding rig tension on the 18, I've never found it to make an appreciable performance difference other than to say that if you're racing, you want the rig to be loose enough that the mast can easily rotate to at least 90 degrees downwind. So this is how I set up my boats. For the beach boat, I don't want the rig flopping around and I don't want anyone screwing with the pins, so we hang on the trap lines and set the rig as tight as we can just using crew weight. For racing, I want the rig slightly loser, so we do the same thing but go up one hole on the adjuster. That's all there is to it.

Regarding jib halyard tension, as others have said, its a good idea to preload the forestay. Using the main blocks and the main halyard is the best way to do this. Once you've rigged the boat enough times, you can set the halyard by feel wirhout using preload. I've never felt the need to loosen the jib halyard on my beach boat after sailing.

Also, the shroud tension has very little effect on forestay tension forestay. Forestay tension (and jib luff sag) is controlled by mainsheet tension. Downwind, the jib luff may sag slightly if the rig is real loose, but upwind its all mainsheet.

sm

Oh crap, ok,
So only way to set proper forstay tension is set rig main sail and sheet it in all the way? So no setting forstay tension on the trailer?
Shroud tension is set before forstay tension correct?

I think I'm currently running a little too loose, there's prolly 3 or so inches of back and fourth travel in the shrouds at the 3rd hole down, I think I'd feel more comfortable one hole further down.
But still need to understand forstay tensioning

Or no, do as I did and hang off the trap and set tension to shrouds, then hold mast froward and have someone set the forstay tight? Then raise jib and set luft tension, that easy?
Side to side play, 3-5" depending on wind?
Just looking for the general setting to adjust from.

Thanks

Per the performance manual,

Push in on one shroud with a moderate degree of pressure. Measure up 3 feet from the base of the shrouds and put a tape measure across to the other shroud at the same point.

"If you can push the shroud in to 74-1/4" you have loose shrouds, or position 1. If you can push the shroud in to 77" you have position 2. If you can only push the shroud in to 79-1/4" you have tight shrouds, or position 3--the maxium amount of shroud tension you will ever want to carry.

Position 1: For all crew weights and sea surfaces in light wind
Position 2: For all crew weights and sea surfaces in moderate wind
Position 3: For all crew weights and sea surfaces in heavy wind

You're mixing up setting forestay tension with setting jib luff tension.

There really is no "forestay tension" per se. There is mast rake and rig tension. The hole you chose on the forestay determines the amount of mast rake. Then you adjust the position of the shroud adjusters to set the rig tension. Yes rig tension will impact forestay tension to a very slight degree, but mainsheet tension is really what dictates forestay tension. The mainsheet acts as the backstay on a Hobie.

When setting the jib luff tension, you want to be sure you preload the forestay. To do this, you can either rig the mainsail and pull on some sheet tension, or just connect the main halyard to the back of the boom, raise it up, tie it off at the mast base, and pull on the mainsheet. If you don't preload the forestay, then you run the risk of over-tensioning the jib halyard to the point that the forestay is no longer taking any load. Then when you pull on the mainsheet, you will break the jib halyard or the jib.

sm

Bingo!
That says it all... you need the rig loose enough that you can rotate the mast easily to 90-100deg.. or just slightly forward of the front beam...

_________________
Paul Evenden
NRO, RMMCC, CJ