Discussion in 'Laser Talk' started by bob-a-long, Jan 4, 2004.
Is it legal to bolt the blocks onto your boom as i have heard that the rivets often break.
Not sure if you are talking about the stainless eye straps that are riveted to the boom, or the blocks that are riveted to the eye straps. In either case, you can replace the rivets with bolts. I haven't seen anyone break the rivets in the blocks (older boats had blocks with screws holding them together, those should be replaced with bolts/nuts).
The aft eye strap is more prone to loosen over time then the front strap (more load), and it's very easy to take one long bolt and go thru the forward hole of the clew fairlead and down thru the aft hole of the eye strap. I haven't found a need to thru bolt the front of the eye strap, or the mid boom eye strap.
I've never really heard of a rivet breaking unless the eye strap isn't strong enough. But while we're on the subject of booms, does anybody else's boom bend a lot when they have the vang on hard. Mine does and it looks funny. In fact, one of my friends has a permanetly bent boom from too much vang load. Is this normal?
I don't think the strength of the eye strap plays into the rivet breaking. I have seen two situations - one is the use of aluminum rivets, where the load causes the rivet to break, and the second is with stainless rivets, where the load causes the hole in the aluminum boom to enlarge, allowing the rivet to pull thru.
As far as booms bending - yes they will bend and get bent due to high vang loading. If your boom is not currently sleeved with the class approved sleeve, I recommend adding the sleeve, it makes the boom much stronger thru the vang attachment area.
With the new 15-1 vang, and today's low stretch line, you need to be aware that you can overvang easier then with the older vang system. At a minimum, make sure you aren't sailing around between races overvanged, I always release mine all the way off after each race (and don't set it again until after the start of a race)
You'll notice the bending boom most when you are overvanged and when the mainsheet is not two-blocked as all the load pulling up (from the sail) is only countered by the boom vang. When you are two-blocked, a portion of the load is countered by the mainsheet at the end of the boom.
I would suggest bolting all boom fittings ASAP as failure is common and if the hole has increased in size (due to steel/aluminium corrosion) then a quick fix of a new rivet will not fix the problem before the start of the next race...
I also suggest bolting the boom. Here in Malta wind is often strong and that is the most effective way of preventing any boom problems.
Sounds like a great idea, bolting them, but how would you actually bolt them? Are you talking about just using a big screw or do you actually mean bolts. The problem with bolts would be getting the nut on from the inside of the boom....I guess you'd have to make a hole on the top side of the boom which seems like it's weaken the structural integrity of that part of the boom.
Check out drLaser for details of how to get a bolt to protrude out of a hole in the boom with the head on the inside. It is possible. The godo thing is that once it is done it is unlikely you ever have to do it again unless you buy a new boat.
You hold the nut with a pair of long pointed pliers and insert it at the end of the boom. This works for the eyelets at the end. For the other fittings, i attach the nut to a long enough wooden strip using a drop of hard metal. When i attach the bolt to the nut from the other side i tighten the bolt and then at the end i break the hard metal drop. It takes some playin around but its definitely worth it. Another possibility is that of using monel rivets and changigng them often. Anyway my current boom is bolted in the way i have described and has regularly been punished with winds of up to force 7 for up to 3hours at a time. Happy sailing.
Great idea, thanks!
I've had a few older boats, and on one of them, the spars were in good shape, except there was alot of oxidation around the fittings, I believe this was due to the differance in material between the spar, the fitting and the rivet. But I'm only a Maritime Operations and Technology major, I don't know too much about chemistry. Either way, it was blowing a good 25+ out and I went out, low and behold the rivet on the eye that held the main sheet block on the boom failed, not fun. So they do fail, under extreme conditions, and I guess you can legally bolt them, in fact I think I've seen a kit to do it with on APS, but not too sure. Anyway, back to work for me.
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