I've got a Reg White Tornado, ca 1981. It's been in a barn for 20 years, but we've dragged it out and sailed it a bit last summer. But there's a problem (isn't there always?). When we took out the long (i.e., outer) bolt from the main beam on the port hull, it was really tough to undo...and when it came out, there were metal bits stuck in the bolt-threads. It's pretty clear that (a) the stainless galled, and whatever nut is embedded in the hull has now lost some of its threads, and (b) I'm gonna have to do something about it.

Anyone who has one of these boats know that the bolts are not only metric, they're some weird metric size -- the bolt wants a 15mm (!) socket, which might make it something like M9. Anyhow, it's amazingly close to a 3/8 UNC, so I figure that perhaps I'll replace it with that along the way. (I've already replaced all the rear-beam bolts with 3/8 UNC, since they and their nuts are all completely removable.)

My question is: Does anyone know what the internal structure is beneath the main beam? Is there a nut in there, embedded in the epoxy and other structure? Is there a tapped stainless plate perhaps? Can I perhaps come at the nut by cutting through the topsides (not the deck or beam seat -- the SIDE of the hull), remove it, and replace it with a nice shiny new 3/8-16 stainless nut, and then patch up the hole I made?

If you know the answers, or know someone who MIGHT know the answers, or you have some photos/drawings of the internal structure, it'd help me get this old thing back on the water, and give my kids a chance for a bunch of fun this summer. I'm just not too comfortable playing with it in a state where the most important bolt in the boat might fail.

Thanks in advance for any help or advice you can offer.

John

If you don't get the answers here there is a fairly active tornado group on yahoo and they frequently talk about older Reg White tornados.

perhaps consider tapping the nut the next larger size and putting a slightly larger bolt?

Thanks for the suggestion. I DID think about that a little, but I have three worries, in increasing order of concern: (1) I don't like the idea of removing any structure as I drill for the larger size bolt, (2) the nut (if that's what it is!) is quite deep in the hole, so I might need a quite long tap, and it's not clear how much space there is beyond the nut for the tapered part of the tap to go, and (3) tapping stainless is no fun, even with lots of cutting oil, and if I break off the tap, I'm in REALLY deep trouble. It's possible that I'll still end up going this route, but as you can see, it makes me a bit nervous.
--John

I would try tapping it, worst case you break the tap and you have to do your original plan anyways.

Having owned and sold a number of Sailcraft Tornados, although all earlier than yours, I can say they all used (3/8-24) bolts for the beams. If yours has a weird metric size, perhaps someone used them and forced them into the holes.

Having said that, it doesn't really matter, does it? You might be successful with a Heli-coil insert.

Good luck with your drilling. I'm pretty sure it is a plate that is imbedded in the GRP, so you have a little wiggle room.

Should have said 3/8-16 UNC (COARSE THREAD)

might be an idea to take the bolt to an engineering supplier and find out what it is

or use a micrometer to accurately measure the thread diameter, count the thread pitch and use a chart to sort it out

the 3/8 -24 above is probably a fine 24 threads per inch

http://www.nutsandbolts.com/38-24-x-1-fine-grade-8-hex-bolts-hex-head-cap-screws-qty1-p-1578.html

http://www.nutsandbolts.com/technical-info-threads-per-inch-reference-table-c-43_268.html

http://www.vsource.org/VFR-RVF_files/Boltthreads.htm

http://www.engineershandbook.com/Tables/metrictapdrill.htm

You said there were nuts under the rear beam bolts. Can you feel up there or use a mirror to look under the saddle and tell if there's a plate glassed in. Maybe the bolts were stripped out there also and someone just used nuts because it was easy. I doubt very much that the thing was held together that way, just nuts.

I would clean out the hole. Use a brush and some compressed air. You should be able to tell if it's stainless or aluminum. Then you can plan the next move.

Mugrace72: This isn't a sailcraft of canada boat...I used to have one of those, and this is quite different. But your conjecture about the weird bolts could be correct. At any rate, you're certainly right that it doesn't really matter. I'm never going to find a tap this size, or a replacement bolt!

Erice: These bolts are definitely a little odd. My micrometer says the head is 14.98mm, which is more than 9/16. The shaft is 9.49mm or .3735"...so it could be 9.5mm metric, or 3/8 standard. The thread spacing seems to be 1.61mm or .637". Yeah, I know. I don't believe those numbers either. Maybe they're Whitworth (!).

Catman: the attachment for the REAR beam is all done through the inspection port. Two short HORIZONTAL bolts that go through a vertical stainless plate attached to the rear beam, and one long vertical bolt though the beam-end and saddle into the hull. I just looked under the saddle, and there's SOMETHING that's about 1" wide by 2" long by 1/2" thick glassed to the bottom of the saddle, but it looks more like a piece of fiberglass than like metal. There ARE washers between the nuts and this reinforcement, but perhaps I'll stick in a piece of 1/4" aluminum to help better distribute the load.

Up forward there are two threaded rods sticking up from the deck on the inner edge of the hull, and a stainless strap that goes over them held down by a couple of nuts to hold the beam on. On the outer end of the beam, there's the bolt I've been talking about...which was intended to screw into this metal backing, whatever it might be.

Anyhow, now that I've had a better look into that bolt-hole, it appears that up forward there's about 3/8" of saddle, followed by about 1/2" of metal, whose threads are almost completely stripped. I guess I'm glad I never looked closely before. I would have worried. It LOOKS as if the metal's stainless. I can't seem to scratch it easily with a screwdriver, the way I could if it were aluminum.


There's also lots of space below the metal, so I think I can safely drill and tap it. Maybe I'll go with a 3/8-16 helicoil; maybe just with a 7/16 bolt.

Thanks for all the thoughts and suggestions, which got me to look more closely at what I've got. With luck, there'll be one more Tornado on the water this summer!

-John

if the thread spacing is tricky to measure individually

either count how many threads in 1" 25.4mm for tpi

or measure the distance for 10, 15 or 20 threads. write that down, then measure the distance trough to trough and divide by 10, 15 or 20

and if you still think it's whitworth

http://en.wikipedia.org/wiki/British_Standard_Whitworth

machine shops should have pitch gauges, if you know someone with a tap and die set they often have pitch gauges too

my old nacra apparently has a strap of brass set in the glass acting as a "nut"

alloy would probably be more likely than stainless as stainless bolts going into stainless threads in a marine enviroment sounds like trouble

tapping a new over-size thread into a alloy strap should be dead easy

The idea about just going up one bolt size would be the best. Use anti-seize on the threads.

tef gel

The Reg White Tornado's that I have experience with, used some type of alloy plate, glassed into the hull. It would be unusual to use a stainless plate on a Tornado. The extra weight of stainless could be better used somewhere else and it's easier to fix stripped threads than galled stainless on stainless(broken bolt, twisted plate,...).

I have tried all of the fixes in this thread (and couple of others that were really bad ideas) and my preference is heli-coil. I have had no problems with my heli-coil inserts. Be sure to use the correct insert. Inserts into aluminum alloy are normally coated and may require an adhesive or primer. On the recommendation of a friend, I bought some at a motorcycle shop and was told "This is the best kit, it's made for a jet ski". The inserts are black coated and I am guessing they are heli-coil Primer-Free. One big advantage of a heli-coil is, you can remove them and put is a new one. I suspect a heli-coil will outlast my hulls.

No matter what you use, use anti-seize on your bolts