Aluminum hull advantages and disadvantages?

Silvertriton · 05 July 2013, 20:55

Hi I am looking for a 24-26 second hand rib with deep v hull with 1 or 2 outboards and was wandering what would be the advantages of an aluminum hull? I suspect it may be lighter and be more resilient than fibreglass but not sure? When looking for a second hand aluminum hull besides the obvious corrosion issues is there anything else I should look out for?

I intend to do regular runs 40/50nm off-shore for spearfishing. I was thinking of double outboards for safety but if the risk of floatsome damage is high and it may damage both o/bs at the same time, wouldnt a one big o/b + kicker be a safer option besides the weight saving?

captnjack · 05 July 2013, 21:34

Aluminum will be quite warm in the tropics - hard on bare feet. It is noisier, lighter, stiffer, and considerably more expensive than GRP. Its harder to make complex shapes (like a stepped hull) from ali compared to GRP.

Easier to repair is a bit of a myth. Once ali has been in salt water it is contaminated and quite a bit harder to get clean welds on. Its much tougher for beaching, although beachng a 24+ ft boat is dicey anyway.

I wouldn't expect many ali boats in the southeast (small Jon boats being the exception), and even less likely to find a RIB in ali. So you may be primarily looking at GRP anyway.

I wouldn't expect lots of logs and stuff down there compared to active logging areas like BC and southeast AK? What debris do you see lots of?

Silvertriton · 05 July 2013, 21:49

Thanks Captnjack. I have never used an aluminum boat but I though that if it is painted and especially if the deck is covered with a non slip polyurethan paint it would not get too hot right? Here we see a lot of logs and assorted floatsome.... what sort of power would you think a 24-26' in aluminum would need for the use I suggest above?

captnjack · 05 July 2013, 22:26

You really can't paint an aluminum deck and have it hold up. Microscopic scratches will let in salt, the aluminum will corrode underneath, and the paint will bubble. Left open to the air the aluminum will corrode a little but with no white flaky powders or anything. Just go to any scuba shop and look at painted aluminum scuba tanks vs the bare metal ones and you'll see the obvious differences in appearance/wear/tear.

Some of the yachts with aluminum wheelhouses and such are painted up here (hulls are typically GRP or steel). But nobody paints a work boat in the PNW or Alaska. Aluminum is freezing cold in cold temps and broiling hot in hot temps. Just the nature of the material.

I don't really think its a question of what something should or shouldn't be powered with. If you are in the used market in North America you have a very limited selection of hull materials and power in the 24ft range at all. The only ~24-26ft RIB like things around here are Protectors imported from New Zealand and the military style 24ft Safeboats which are not really RIBs (foam collar) and used by the USCG and local police departments. Both use dual outboards. I have never seen a Safeboat in private ownership and they are made right down the road from me. So I'm not sure they even sell them to non-government buyers.

Good luck with your searches.

Silvertriton · 05 July 2013, 22:55

Again many thanks Captnjack, I guess the same issues you mention above will also make the glueing of the sponsons to thealuminum hull difficult or is this addressed by roughening up the contact surface?

captnjack · 05 July 2013, 23:01

My hypalon tubes are glued onto my aluminum hull. 2 part hypalon glue is seriously tenacious. Boat was built in 2007 so I don't know for sure, but I suspect the hull/tube bond will outlive the tubes themselves.

jyasaki · 06 July 2013, 16:42

Quote:

Originally Posted by Silvertriton

Again many thanks Captnjack, I guess the same issues you mention above will also make the glueing of the sponsons to thealuminum hull difficult or is this addressed by roughening up the contact surface?

I clean the aluminum (Alumabrite), then cold anodize it (Alodine 1201.) Glue sticks to it pretty well after that.

Oh, and Jack: Safeboat does sell to civilians, but they're damned expensive. Most likely a pretty good lead time as well.

jky

clloyd · 07 July 2013, 05:18

Unless you need the impact and scratch resistance of alum (aka workboat), why go that way? Fiberglass hulls are IMO waay more friendly. There is a wide range in quality of how grp hulls are put together. Look at the hurricane 733 and willard 730 for a bomber 24' that would be amazing in panama. You are making me jealous. There are even workboat versions of these with metal beaching shoes....and even dive doors. Happy hunting.

If you really think debris would knock a drive off, look for or convert to a hamilton jet. Some hamilton jet willards were made.

ShinyShoe · 07 July 2013, 08:22

In the smaller end of the market aluminium hulled RIBs seem to be a LOT lighter and consequently need less power and so drink less fuel... Tha'd be my reason for looking at a aluminium RIB. Clearly that depends on the price of fuel. But a litre is about £1.40 here which is probably close to $2.00(US). I guess thats probably twice what you pay in the states.

Don't know if fuel costs in the South Americas are as cheap as the states. But it might be a driving factor.

mister p · 07 July 2013, 10:20

Don't know if fuel costs in the South Americas are as cheap as the states. But it might be a driving factor.[/QUOTE]

Fuel prices being a driving factor. I like that a lot.

jyasaki · 08 July 2013, 01:39

Quote:

Originally Posted by ShinyShoe

Don't know if fuel costs in the South Americas are as cheap as the states. But it might be a driving factor.

I think the OP is Panama City, Florida.

jky

kubcat · 08 July 2013, 07:44

I have an aluminium 2.9m RIB and an aluminium 5.6m RIB. I also have a 4.7m fibreglass RIB and an 8.9m fibreglass RIB.

The aluminium ones seem stronger and lighter for their size. They are noisier when they hit chop making them sound not as robust, but they are pretty tough. They ding instead of crunch when you hit something very solid. Don't have to worry about rot with the aluminium. Yes the aluminium does eventually corrode but based on other boats I have had it probably outlives the fibreglass. The fibreglass usually looks better because of the shapes that can be formed and the colour.

Personally I think who built it and how they built it is more important than the material.

Pikey Dave · 08 July 2013, 13:26

neil.mccrirrick has an aluminium RIB, drop him a line & ask his advice.

Silvertriton · 08 July 2013, 14:09

Many thanks for al the very interesting suggestions and comments. I have been considering aluminum since I wish to have the combination of strenght, and low weight for a 7-8mt size to facilitate shipping via sea container, trailering and lower fuel consumption. I am based in Ciudad de Panama (not Panama City) but I work in the humanitarian sector and often work in countries where there is little chance of sea rescue and wish to have the largets size /lightest weight I can get in the second hand market since I will definetly not be able to afford a new rescue type aluminum RIB.
I am not in a hurry and I will keep an eye open for aluminum but othewise I will definetly consider fibreglass.

neil.mccrirrick · 08 July 2013, 14:39

Hi. As Dave says I have a 7m aluminium rib with a 140 tohatsu on the back

Any questions please feel free to ask happy to share my experience to date

Very happy with mine so far. Feels very solid etc. FYI my tubes are fitted by sliding them onto grooves. In theory they would come off for maintenance etc. I suspect reality is it would be a helluva job

jyasaki · 08 July 2013, 14:50

I wouldn't avoid glass. Lot easier to come by, and, unless you're planning on a lot of boating in shallow rocky areas in water with a lot of movement, the strength won't come into play much.

The fuel hit from glass vs aluminum won't be a deal killer, IMO. If it was, more glass hulled boaters would be trying to run solo with no gear on board.

I went with aluminum primarily because I was spending a lot of time off rocky shores, often in pretty close. Of course, once I got the more capable boat, I've been spending more time further offshore. Go figure.

jky

Silvertriton · 08 July 2013, 15:10

Hi Neil and Jyasaki, what type of aluminum boats do you have and any pics? I have just tought that another advantage of aluminum hulls could be that they may be safer and easier to rig for lightning shields?

captnjack · 08 July 2013, 15:20

The only "lighting shield" you'd possibly want to consider is a mast. As in a sailboat mast, well grounded to the sea. And you still don't want to be hit by lightning, it will fry every electronic thing on the boat and might kill you anyway. Highly unpredictable.

There's pictures of my 5m ali RIB in my gallery. If you are trying to ship this around the globe via container I don't think aluminum is going to save you anything vs GRP.

neil.mccrirrick · 08 July 2013, 15:55

you have a PM

Silvertriton · 08 July 2013, 17:52

I am not sure but it looks like an aluminum RIB with an A frame connected with the consolle would provide some very good protection and dissipation of a lightning without any modifications in comparison to a standard GRP hull.... to avoid derailing of this Alu hulls conversation, I have started another thread regarding lightning shield on RIBS.