Looking for Rig Adjustment reference book

[bstruebing]

I have a 20' trailer-able sloop on the great lakes. When I step the mast next week, I want to dial in the rig, get all the stays and shrouds properly adjusted, tensioned, ect... Can anyone recommend a good book so I can teach myself how to do this? Of course this knowledge would be carried over to a larger vessel once we exit the rat race.

[boatman61]

Hope the basic's here prove helpful..


It is essential that every owner should know how to adjust the standing and running rigging on his boat. Even if you have the rigging set up by a yard, after a period of sailing due to the slight stretch in the rigging and perhaps some slight movement in the structure of the boat, the rigging may be out of adjustment and need setting up again. Apart from this, surely, half the fun in owning a boat is adjusting it to your own satisfaction, which brings the confidence in your own ability to keep your boat in a ‘seaworthy’ condition.

Standing Rigging The standing rigging must be adjusted correctly for two reasons:- a) To ensure the structural integrity of your mast b) To ensure that the mast and forestay are the right shape to suit the cut of your sails.
If we assume that you have the mast approximately upright in the boat with all the rigging attached, and hand-tight, then, the correct adjustment can be carried out as follows:- a) Slacken off completely the backstay tensioner and take up all the slack in the backstay and forestay by tightening the forestay rigging screw. b) Tighten up the backstay tensioner to put a reasonable amount of tension in the backstay. As the mast is deck stepped, this, of course, will automatically tighten up the forestay. c) Now tighten up the cap shrouds as hard as you can using a tommy bar, say about 6" long. Measure the amount of thread taken up in each rigging screw to ensure that the mast is upright in the boat. The cap
shrouds have been manufactured exactly the same length, therefore, if you keep both rigging screws adjusted to the same length, then, the mast must be upright. d) Now tighten up the lower shrouds to about the same tension as the cap shrouds, ensuring that the mast is straight athwartships by sighting up the mast mainsail groove, adjusting the relative tension of the port and starboard rigging screws as necessary. (Editor’s note these need to be a lot tighter than the upper shrouds on a ‘34’) e) Tighten up the inner forestay (the babystay) until there is about one inch bend forward in the mast at cross tree height. f) Now, go round and lock securely all your rigging screws, this is most important. DO NOT LEAVE YOUR BOAT ON THE MOORING OR GO SAILING AT ALL WITHOUT LOCKING ALL YOUR RIGGING SCREWS, OTHERWISE, THERE IS A DANGER OF YOUR MAST FALLING OVERBOARD. While you are locking the rigging screws it is a wise precaution to also check that all split pins have been adequately opened on the clevis pins. Lastly, bind any offensive sharp edges of clevis pins, split pins, etc, with PVC tape to stop damage to your sails or your hands.

On the question of how much tension to put in your rigging, the objective is to tighten up the backstay tensioner as hard as is necessary in order to eliminate or at least reduce sag in your forestay when hard on the wind. The sail maker will have cut your genoas assuming a certain amount of forestay sag which Sadler Yachts will have discussed with their sail makers. The cap shrouds and lowers should be tightened sufficiently until slackness appears in the lee rigging when hard on the wind and the angle of heel becomes about 15° (Editors note personally prefer at least 20°). Most people will find that this means the caps and lowers must be tighter than they imagine. The tension in the babystay must be as previously described to give a bend forward of the mast when the boat is on the mooring with the backstay tensioner tight. This is for two reasons:- a) To give the correct shape of mast to suit the mainsail. b) To prevent the mast from panting when underway or on moorings. It is important that the mast should not be allowed to bend backwards in the middle when you are sailing, and this is most likely to happen when the mainsail is deep reefed and the head board of the mainsail is pulling the mast backwards. Now for the practical trials, and although you have adjusted the mast and rigging to the best of your ability, the criteria is ‘how does it stand when you are sailing’. If you are sailing in, say, a force 3-4 breeze and close hauled, go to the foot of the mast and sighting up the sail groove, the mast should be straight athwartships. If it is not, then, you should heave to, adjust the lower shroud on the particular tack you were sailing and then, try again. When you have got it right on one tack check the other tack and ensure that the mast is straight again. Double check that when you are sailing hard on the wind that you still maintain a slight bend forward at crosstree level. When you have finished sailing, it is a good idea to relieve most of the tension on the backstay tensioner.

[john61ct]

Wow, great write-up

[thomm225]

Boatman's writeup is probably closer to they way riggers do the rigging adjustment, but when I did mine 5 years ago, I used the percentage of cable strength method

You can look it up on the Loos site, but I think it's around 10-15%

I borrowed a Loos Gauge from our local used sailboat parts store and I ended up with 440 lbs on all stays except the forward lowers which I set at 550 lbs for a bit of prebend.

I also made sure the mast was straight laterally. Back to front is off a bit because the backstay is out of adjustment and I didn't want to put any money into the rigging unless I'm going to replace it all

I watch the shrouds every now and then to be sure the leeward one doesn't get too slack on one tack or the other.

Besides that I just glance at the prebend every now and then to see that it hasn't changed which tells me the rigging hasn't stretched much and that my good old boat isn't getting warped due to over tensioning the rigging........

If you have diamond wires on your mast, you set the prebend with those if desired

[atmartin]

"Illustrated Sail & Rig Tuning" by Ivar Dedekam

[bstruebing]

Amazing reply. Thank you.

[John_Trusty]

As a former owner of a 20-something trailerable, I recommend the Loos gauge to check your rigging tune until you get really good at it, like Boaty. More than the larger boats normally discussed here, we have the added fun of removing the entire rig to trailer. Getting the thing tuned once is bad enough (it's about a half-hour of playing once you're fast, or an hour if you have to think about each step). After your day of sailing, you loosen everything and take it all apart. The next day, you need to fit it all again. The Loos gauge allows you to quickly re-set everything close to perfect, after you center the mast, of course.

[thomm225]

Also, depending on how big your boat is you may have those multi-slotted mast adjusters.

With those once you find your correct settings, all you will have to do is remember your settings each time you setup and use the same holes ........at least until your rigging starts to stretch.

Also, usually on lightweight 20' daysailers most folks just go by feel after a while....and use the matching slots on the adjusters/turnbuckles

On racing beach cats, we set the prebend with the diamonds (using a Loos Guage for the 1" to 2" of prebend) and the shrouds with someone hanging on the trap lines for tightness then use matching holes on both side mast adjusters

[charliehows]

Originally Posted by John_Trusty

As a former owner of a 20-something trailerable, I recommend the Loos gauge to check your rigging tune until you get really good at it, like Boaty. More than the larger boats normally discussed here, we have the added fun of removing the entire rig to trailer. Getting the thing tuned once is bad enough (it's about a half-hour of playing once you're fast, or an hour if you have to think about each step). After your day of sailing, you loosen everything and take it all apart. The next day, you need to fit it all again. The Loos gauge allows you to quickly re-set everything close to perfect, after you center the mast, of course.

thats a great explanation for why its a real boon if you got to learn how to sail on small boats - thanks to my long departed father for dragging me out on his bloody horrible little rothmans and yelling at me til i figured how to help keep us out of the drink...

[DougR]

Selden Masts makes a small book on tuning and tensioning the various types of masts which is very helpful.....single or multiple spreader, fractional or masthead, straight or swept spreader, etc.

You can download the book from their website. I think it's called tuning tips, or something like that.

DougR

[Hoodsail]

another good book is B Toss's "the complete rigger's apprentice", altho of the almost 400 pages only about 1 page addresses rigging tension. I opted to have the mast tuned by a rigger and then came back and measured/recorded the tension with my Loos gauge so I could duplicate it each season. thnks dave

[S/V Alchemy]

Nothing but good answers here. You can use a gauge, a plumb bob, a tuning fork...there's all sorts of decent methods! Just ensure your chain plates are in good order before you start twanging about.

[Near2KR]

This is the pdf of the Selden booklet. Lots of info here.

http://www.seldenmast.com/files/1456.../595-540-E.pdf

[wiekeith]

Originally Posted by DougR

Selden Masts makes a small book on tuning and tensioning the various types of masts which is very helpful.....single or multiple spreader, fractional or masthead, straight or swept spreader, etc.

You can download the book from their website. I think it's called tuning tips, or something like that.

'HINTS AND ADVICE on rigging and tuning of your Seldén mast'. It's a really good resource, as DougR mentioned, and it's free

[s/v Jedi]

Originally Posted by atmartin

"Illustrated Sail & Rig Tuning" by Ivar Dedekam

I second that