Anyone know how tight these are supposed to be? Too loose and you have slop in the platform. Too tight and maybe you could crack the glass around the bolts. Is there a spec like on the lug nuts on the car you're supposed to torque them to 80 ft-lbs and tighten in a crosswise order?

D. Ho
TheMightyHobie18 1067

I've never come across a spec for these bolts. Just good and snug seems to work well - and check them every couple of months as they may work loose over time. To reduce slop in the platform, bed the beams (a forum search should yield several threads on this topic). I coated the threads on the inboard hex cap screws with a little copper based antiseize compound, and assembled the outboard nut and bolt dry, using a nyloc nut. Just use regular hand tools and don't go too crazy tight [the cracking noises will tell you when enough it enought <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />]

These bolts control the hull alignment on a Hobie 18 - there is enough slop in the cross beam holes to affect toe out/toe in by an inch or two. To realign the boat, tramp tension must be relaxed first.

Chris.

the answer to your question is in the length of the allen wrench that comes with the boat. hand tighten the bolts with that wrench.
you can measure your diagonals as you tighten the bolts down, but i think the platform just bolts together in 1 configuration with not much adjustment if the diagonal measurements are not equal. your results may be different though.

The question is: What is the torque value for beam bolts?. The answer is:

I have never seen a torque value for beam bolts. I always guessed that because the condition of boats vary wildy, nobody wants to be responsible for you stripping the threads on an old corroded boat.

That said, a standard practice for 1/4" bolts threading into aluminum is 5-10 ft-lbs. This is for new clean threads. Not dirty corroded threads. For a normal boat, I consider 5 ft-lbs a maximum.

FYI the 5-10 ft-lbs is from a aircraft practice. The rest of the practice says "don't thread steel bolts directly into al in a saltwater environment".

In reality, apply anti-seize for al/steel to the bolts and threads. Clean the threads every couple of years, with a tap. Just get the bolts snug and check them frequently and keep a heli-coil kit for Al/steel handy. Pep Boys sells a good SS heli-coil kit for head bolts going into aluminum motorcycle blocks.

All the bolts and bolting bars I have seen on the 18 were all SS.

Diagonal measurements do not reveal toe out/toe in. Only side to side measurements will do that.

I always thought mine were aluminum and treated them as such. I have never seen what is inside an TheMightyHobie18 hull.

To have zero toe in/toe out and a square setup of the hulls/crossbeams do this...

1. Make a mark on the top aft of one hull then make a mark in the exact same place on the other hull.
2. Make a mark on the top bow of one hull then make a mark in the exact same place on the other hull.

3. Check your work. You now have four marks on your hull, the distance between both marks on the left hull should (and needs to be) the same as the distance between the two marks on the right hull, if not repeat steps 1 and 2 until you get it correct.

4. Setup up your hulls with the cross bars attached but without tightening the bolts snuggly, you will need to have a little slop for the next steps.

5. Measure the distance between the art mark on the left hull to the bow mark on the right hull.

6. Make the distance between the aft mark on the right hull and the bow mark on the left hull the same as the distance measured in step 5.

7. tighten the bolts

8. Check your work. Remeasure as in steps 5 and 6. If the measurements are the same from hull to hull/ aft to bow then you have paralell hulls and a square setup. If not repeat steps 5,6 7 and 8 until things measure out.

This is basic geometry and it works for anything that needs to be square or rectangular. The more accurate your measurements and the marking of the hulls the more accurate the results.

BLS

Thanks everyone,

I think I lost the hex wrench that came with the boat. The boat is almost 30 years old. I have a 1/4" allen wrench with about a 3 inch handle on it. Would that work?

D. Ho
TheMightyHobie18 1067

A couple of comments:

1) I have never seen a torque for any cross-bar bolts on any Hobie Cat. I don't believe that they specify one. On my 18, I have always made the inboard bolts as tight as possible with a standard allen wrench (They are difficult to make really tight anyway due to their location). The out board bolts I usually make moderately tight using a socket wrench with a 1/2" drive. If you're really worried about it, I believe you can look up the maximum torque for the size and grade of the bolt (this is designated by the hash marks on the head of the bolt)

2) The inboard cross bar bolt threads into a bracket with stainless steel threads. There is basically a stainless nut which is pressed into the aluminum bracket. The aluminum bracket is riveted to the inside of the crossbar. So the threads are stainless on stainless.

3) I have always questioned the practice of trying to align the boat by squaring it up using a tape measure and then tightening the crossbar bolts and trampoline. I suspect that it is a lot of work done in vein. The first big wave or gust of wind, and the boat is going to loosen up and settle in to it's natural alignment. Personally, I think it's better to trust that the manufacturer has done his job by making proper alignment jigs, etc., and just keep the boat tight. I doubt that you can effectively align and maintain alignment the boat using only the slop in the crossbar bolt connections and the trampoline.

sm

torque it till it strips.... then back it off half a turn