Mast & Booms

I won’t go into masts out of column, rake, tapered, fractional rigs, Euler's Formula, Skene's Scantlings, etc. just some basics for a good visual inspection. Aluminum, steel, fiberglass, wood or whatever you have must be to kept in good condition. It doesn’t have to be pretty, but the paint on that spar serves a purpose. It’s at a minimum, a protective coating for corrosion (metal masts), water and bugs (wood masts) or ultraviolet sunlight (fiberglass masts). Usually, when I see deterioration at a spar while conducting a survey, the paint is flaking or gone at the problem area.

Sheeves, goosenecks, tangs, fittings, boom end caps, and all those items that make a mast or boom also have to be visually inspected. A missing cotter pin that holds the clevis pin in place, can and probably will create a disaster. That stainless steel fastener that was installed into an aluminum mast without a dielectric compound or into a wood mast with a real good sealer will fail, I just can’t tell you when or what you will be doing at the time. All those fasteners that hold the halyard winch on an aluminum stick could let go or maybe add the “swiss cheese” factor to that portion of the mast. Without that real good sealer in a wood mast or spreader, it can turn the new rig wiring you bought and installed, to a useless expenditure.

Mast Steps

Lots of the masts I see are sitting in water, deck or keel stepped. That water is in the mast step itself and shows that deteriorating coating I mentioned. Minimum, ensure there are limber holes for the water to get out. Next time you pull the stick, clean it up and maybe put a little paint on the inside of the mast, and if it’s a older boat ensure the support below the mast step is sound. Deck stepped masts, after years of water leaking into those unsealed fasteners, rot out that “core” in the fiberglass sandwich construction and collapse it some. You can tighten to the end of the turnbuckle and the wire is still loose. Keel stepped show some of the same problems, once in awhile I see new a mast step on old boats, usually a new grid pattern where the mast fits over the new step instead of in it. Same problem, where are the limber holes for water that gets inside the mast and puddles in the step? How about the structure below that keel step, delamination, stress fracture, split or rotted wood? Again, without a “solid” structure top to bottom, new wires could be a waste of money.

Wires and Fittings

I like swage fittings on 1x19 stainless steel wire, it’s what I am used to sailing lots of miles on and have worked with the most. Not sure what grade of stainless you have, 302/304 or 316? 302/304 is not as corrosion resistant as the 316 and as you walk around looking at 302/304 wire you can usually see what looks like one strand of those 19 appears a little rusty or brown. The benefit of 302/304, 1/4" wire is that the breaking strength is 8200 lbs. – vs – 6900 lbs. for the 316 wire. Some folks like 302/304 stainless, some 316 stainless, some dieform, some 7x19 wire, some galvanized steel, some rod rigging, and some the new kevlar, but the basics on what to look for are the same, ANY DETERIORATION! Any broken stands, cracks, kinks, or stretch on a wire, rod or its fittings, replace it. Brush away any rust on a fitting, toggle, or turnbuckle and look real close. Look at the clevis pin, is it the correct size? I have seen more than one rig where the wire, turnbuckle, Sta-lok or swage fitting and toggle are all set up for ¼” wire but the clevis pin is 3/16”.  Look at the hole the clevis pin is in on the chain plate, is it round or oblong? Oblong means point loading. What you are seeking is the weakest link in the system. I also have seen folks try to “game” the system, meaning if the original specifications are for ¼”, 316 wire, let’s go 2 sizes up 5/16", 302/304 wire, and make it bullet proof! Doesn’t work like you think even though that rigging design has a built in safety factor, from what I have read a 3 or 4 to 1 factor, some are 100 to 1, and from the breakage of some of those "sleds" it appears to be a 1 to 1 factor. Without knowing the detailed information of the design parameters, your gambling. First when you “tune” (tighten) a rig usually to 10% to 15% of its breaking strength that would mean 690 to 1035 lbs for 316, ¼’ wire on a torsion gauge. Now you change that to 5/16”, 302/304 wire and that 10% /15% rig tension is now 1250 to 1875 lbs, or maybe sailing in a 20 knot breeze, sitting at the dock, without any sails up? Load factors and deteriorated fittings are the cause of failures. 

Adding bigger wires have added more compression loading to the mast and more tension to everything it is attached to, so what happens to the load factors when you get caught in a 30 knot blow? I have seen a wood boat pop a bottom plank and destroy the structure below step, a fiberglass boat trying to drive the mast thru the hull, etc. Thinking about doing that, check with the boat bilder or a Naval Architect first.

SAILS

Here is a UK site all about sails, how there are made, flown, trimmed, etc.

Don't know the sail area for your boat and want to see those load factors? See one of the many sail area calculators on the net at http://www.image-ination.com/sailcalc.html it has the design areas for many production boats.

Then you can go to this site, just go to Wind Load at  http://www.sailingusa.info/motion_comfort.htm  and figure up the loads at different wind speeds.

Here’s a good site for rigging information, how it’s made, breaking strength, fittings, etc.

www.loosco.com

and a Navtec site for the new "fiber" rigging at www.navtec.net

and Aussie site for the how to on the Norseman and Stalok fittings at www.mauriprolsailing.com/Sta-Lok/stalok-fittings-instructions.htm