Catamaran forebeam shape

Coolness

Eponodyne, you're way behinds the times man, early composites/ fibre reinforced plastics might have included "grown" fibres, but unless you wanna be some "untrendy retro - slip me favourite surf shirt into the next surfboard layup stinkin' hangin' ten, havin' a great time livin' life & enjoying the beautifulul world we live in, carvin' up crystal perfection hippy" you got it all 'rong dood, you can even get look-alike carbon stuff to make you super edgy & real techno strong even if you aint! Just get the vibe of it & be cool man, if you don't have the latest you not in the fabulous groove of the nu millenium! but maybe the groove of the future? who knows, I like the alternate veiw & even have some old homemade from linen & whatever goo blocks & tools kickin' around my workshop/garage & know that my resin encrusted workshirts are pretty tough to wear. My choice of forebeam would be the aluminium with hinged brackets at the hulls & anodised for some corrossion resistance & just bolt it onto some heavy laminate kind of thing thats been proven reliable for a long time. All the best from Jeff

 

Can't we all just build our boats out of hemp and fish glue, man?!?!

 

The amount of bury is going to be the same for either an aluminium tube or a composite one. The only genuine difference between bonding in an alloy or composite beam is the bond between the glass and the alloy. With the area you are planning to sleeve, there should be more than ample strength in the join.

To me, electrolysis should not be an issue if you take the normal measures to prevent it. There won't be any dissimilar metals inside the glass sleeved area anyway. How many thousands of boats are sailing with alloy masts and booms, and how many of them are having significant problems with electrolysis, corrosion or fatigue? No doubt there are some, but a very small proportion, and I would bet most of them have been abused or neglected.

For a racing boat, carbon might be worth the extra money, but for a cruising boat I wouldn't go that way. There is also the day to day bumps and knocks a cruising boat gets to think about, i.e. the forebeam is where all the anchoring "action" happens - a composite beam is likely to be easier to damage, but the extent of any damage may be harder to see or diagnose.

 

Hi everyone, sorry for not responding sooner but I had been on leave the past few weeks. It’s nice to have received all your good advice while I was away.
It looks like the consensus is that the burry is not a problem for a glassed in aluminium tube and that either the alloy or composite tube offer a good solution.

Danny makes a good point that while the aluminium tube alone is the cheapest but may not be the case as a complete assembly.
So I think the next stage for me is to do a full cost analysis for both options.

Richard made a point that round sections tend to twist and bend aft. To counteract this my plan is to put in a slot at the ends so that it fits around a bulkhead and there will be a catwalk in place.

Cheers
Andrew