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5.8 Hull Alignment


dryzabone 644

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Originally posted by HooD:

Are you measuring the tops of the bows or the bottom??? because a 5.8 bow leans outwards to compensate for the original bridal wire that pulls the tops of the bows inwards.

I was under the belief that you should have a degree of toe out ,(bows slightly further apart than the stern)the measurement I cant recall ,depends on how old the boat is ,was it built before or after the introduction of the brinal foil.If you don't run the foil when you crank on the mainsheet this tensions the forestay which pulls the hulls together,without the foil this angle is far greater than if you have the foil,with the foil the tension is nearly straight up.

If in doubt ring up Warren at Brisbane cat center he'll give you all the measurements!!

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Originally posted by dryzabone 644:

OK,

Thanks for the info, looks like I need to go back and re-measure with a couple of different things in mind.

Should I need to adjust the hulls in any way, does anyone have any suggestions as to what method to use?

I don't know if you can adjust it the hulls should line up with the stoppers on the front and rear beam ,this is a factory set up ,I've pulled a couple of these boats apart ,when you put em back together you must mack sure the beams ure sitting flat on there mounts and their all the way up to the stops ,check the saddles are straight and the bolts are tight,(don't over tighten them) ON A OLD BOAT I STRIPPED A COUPLE SO I TAPPED EM OUT TO A BIGGER SIZE AND PUT BIGGER BOLTS IN THEM!!

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Originally posted by REV YUKKA II:

when tensioning bolts into alloy the trick is too tighten the bolt till it strips then back it off half a turn lol. rev

Hey Rev, I will call you next time to help me put a beam back on the boat. So how many ft/lbs torque is that mate before it strips? On Graceland I installed new s/s 5/16" helicoils into the boat before the new front beam was placed into position. They are alot stronger than the original alloy blocks and a helicoil kit is worth about $55.00, better than tapping out to 3/8". Regards Graceland 1216 & 1591.

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OK, I have gone back and checked my measurements, and they came out something like

bow to bow: 2155mm (top and bottom)

stern to stern: 2135mm

port stern to stbd bow: 6215mm

stbd stern to port bow: 6190mm

so, my bows are spread and my diagonals are out slightly. I think I might check how tight the beam hold down bolts are and tighten them about 2Nm looser than Rev's method !!

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As I stated above the boats built pre jib foil to bows would be designed to toe out around 20mm this compensates the bows pulling together under mainsheet tension,boats pre about 1350 did not have the jib foil from new (they were introduced after ,and retrofitted to alot of boats) so I think this is normal,the difference in the diagional measurements sounds alot but 25mm over the diagionals is really bugger all when you think of it all it would take would be a hull to be slightly out of alignment.you could probly put some shims under the beams to fix this ,A couple of mm would probly fix it.

Some of the first 5.8's in Australia were not built in Aust but imported from the USA and I think the first lot built in Aust were not made by the current manufacturer.

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An I often aligned the hulls exactly the same mid way up the bows to mid way up the stern. I set them at the exact same measurement. This was mainly due to how we went downwind then which was broad reaching with both hulls in the water and it was a must to have them 100% perfectly aligned.

It is not as important now, but it is ideal if you can do it. The alignment is done at the rear beam, not the front.

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Well in that case what is the deal with the stoppers on the beams that VillageIdiot mentioned earlier on? Is there a certain amount of slack in them to be able to adjust it? Or is it just as simple as loosening the straps and moving the hulls outwards at the back? I am just unsure as I haven't seen a 5.8 dismantled before.

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This is what I used to run on my 5.8s (1552/1600):

20-25mm toe out with or without the bridal foil even with the foil hulls will pull in 30+mm under mainsheet pressure. Next time you rig pull the mainsheet on on the beach and measure I think you will be surprised how much they do come in. You want about 5-10mm toe-in under mainsheet pressure, otherwise you will be pushing a bucket upwind and downwind in light winds not fast. The foils main purpose was to get the jib lower to get the drive lower and reduce pitching.

5mm prebend in the front beam to stop the beam from compressing under mainsheet tension.

Cheers

(Nothing beats reaching in 25 knots on a 5.8)

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Originally posted by NacraPhelia628:

Well in that case what is the deal with the stoppers on the beams that VillageIdiot mentioned earlier on? Is there a certain amount of slack in them to be able to adjust it? Or is it just as simple as loosening the straps and moving the hulls outwards at the back? I am just unsure as I haven't seen a 5.8 dismantled before.

These stoppers are attached to the underside of the rear beam and incorpate the ends of the dolphin striker on the front beam.there are also some stainless plates riveted to the hull where the stoppers rest!I 'm not sure if the old boats have this??This is set up from factory.the new boats the front beam can only go in one spot the bolts go down through the front beam and into the hull,the rear beam you could adjust by putting shims between the stoppers and the hull plate I suppose?this would straighten the hulls in alignment..

\

Listen to what Scott has said ,He really knows his shit!!

[This message has been edited by Village Idiot (edited 22 October 2005).]

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