Aluminium or Fiberglass speedboat?

[Baneng]

What are the advantages of Aluminium over fiberglass for speedboats used in areas with consistent swell ?

[yokebutt]

Primarily the tendency to deform instead of fracturing when impacted.

[cyclops]

Aluminum boats can jump twice as high as a glass boat. Less than 1/2 the weight.

[marshmat]

In general an aluminum hull can be built slightly stronger for a given weight than a fibreglass one. (Doesn't necessarily mean that an aluminum hull IS better, though, as each manufacturer is different.) The preferred mode of failure, as Yoke mentions, is a major factor. Aluminum, when strained beyond its elastic limit, can still deform quite a bit before it actually breaks. GRP/fibreglass laminates tend to fail suddenly; instead of bending they simply shatter. So the aluminum is probably more forgiving when you launch the boat off a wave and slam the bow into the next crest. Where fibreglass has the upper hand is when you have more complex hull shapes that cannot be broken down into easily developable sections (ie. most speedboat hulls); in this case the composites are much easier to build with than having to stamp and weld dozens of metal sheets.

[Baneng]

Thanks All,
I know that aluminum is better,just trying to convince the boss.

[Deering]

One issue with aluminum boats is antifouling paint. Most paints are copper-based which doesn't play well with aluminum (your hull will corrode and dissolve). Means you have to use a more expensive alternative paint which won't perform as well.

If you're trailering the boat... never mind.

[h_zwakenberg]

As to antifouling:

Years ago a British magazine, I think it was 'Practicle Boat Owner', carried an article on how to make a good antifouling yourself. The author explained how he had purchased the cheapest antifouling around, and added 'tetracyclin', an antibioticum he purchased from his local vet.
Tetracyclin is a broadband antibioticum - the author reasoned that it would kill the micro organisms that foul up our hulls as well, and rightly so.
Afterwards it transpired that the author and/or magazine were threated with a law suite by an US company that produces antifouling that also contains (contained?) tetracyclin...

Worth a little testing, this ?

bye
Hans

[bazza]

I have heard of great results with vet antibiotics added to antifouls. have heard a lot of people complain about the possibility of creating antibiotic resistant sea bugs from this method though.

[RANCHI OTTO]

My own experience with aluminum high speed boats is that the gain in waight is not so important if you will avoid local bottom deformations. Attached a diagram with points derived from built boats.

[h_zwakenberg]

Originally Posted by bazza

I have heard of great results with vet antibiotics added to antifouls. have heard a lot of people complain about the possibility of creating antibiotic resistant sea bugs from this method though.

That might well be a valid objection...

bye
Hans