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Old 20-10-2015, 00:45   #16
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Re: Advice on Aluminum boat Valencin 39, 1985

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If the first owner had the same intend great, if not you will probably have a very difficult (and expensive) time to isolate the hull 'against condensation'.

Good luck and keep us posted!

Carsten

Virtually all aluminium cruising boats will have hull insulation. The thickness varies, but even if only 1 inch is used, the hull will have much better insulation than than even a fully cored fibreglass boat. 2 inches is more common and 3 inches, as we have, is also seen.

The only real exceptions are aluminium boats built with racing in mind. These were quite common, as in the early days aluminium was the lightest way to build a hull (these days epoxy lay ups with carbon fibre etc have taken over, as these are much lighter again).

Aluminium race boats often left out any insulation to save weight. As they became uncompetitive, many of these race boats have been converted to cruising boats. You need to be careful with these boats. Not only was the insulation left off, but they were often constructed of the very thinnest aluminium possible. In some cases even fatigue (which is not an issue with normal yacht construction) can be a problem, as the stiffness of the hull skin is drastically reduced with even a small reduction in thickness. This can cause significant flexing of the hull skin between the frames.

It should be rembered that there are lots of pluses no chance of core rot, no delamination, no hull/ deck joint problems, no osmosis, no keel bolts to name but a few structural advantages.
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Old 20-10-2015, 00:54   #17
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Re: Advice on Aluminum boat Valencin 39, 1985

The boat has very thick insulation (10-15cm).
Pipes and water tanks are plastic. Seakocs are also plastic (or merelin)
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Old 20-10-2015, 04:36   #18
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Re: Advice on Aluminum boat Valencin 39, 1985

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Search around here for posts on aluminum hulls... I know there's some info on the proper aluminum, and construction... I'd hate to see you get into something that gives you significant problems...

Surely where you are there are plenty if local surveyors with extensive knowledge of aluminum construction...
You see... Here is a perfect example of knowing I know something about something without actually knowing what that first something is....

I'm glad all the experts were able to point out their concerns.... Don't be discouraged, but DEFINITELY don't ignore their concerns...
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Old 20-10-2015, 04:49   #19
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Re: Advice on Aluminum boat Valencin 39, 1985

PS

This is NOT you... But if you want to read about an aluminum nightmare...

Breaking All the Rules ...

Also, as I said before... do some searches... There were a ton of threads loaded with info when I looked for this one for you...

We really are hoping this boat passes all the check boxes for you!
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Old 20-10-2015, 05:48   #20
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Re: Advice on Aluminum boat Valencin 39, 1985

The simple fact is that wth a properly balanced rudder very large boats are perfectly manageable with a tiller. For example most of the TP52 fleet and pretty much all of the sixty foot solo round the world racers.

I have a similar sized boat as this one which I converted to tiller steering and would not for a moment consider changing it back. Don't be disuaded by people who might not have experience driving larger boats with tillers.
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Old 20-10-2015, 06:11   #21
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Re: Advice on Aluminum boat Valencin 39, 1985

Well what a hell, called a seller and arranged test sailing for couple of hours this Saturday.
If all goes well, will do the offer (with condition if it will pass a proper survey).
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Old 20-10-2015, 08:11   #22
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Re: Advice on Aluminum boat Valencin 39, 1985

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Amazing. Using copper water pipes in an aluminium boat is madness. Every contact with the aluminium hull would need to be isolated. Even a small area of contact would result in rapid corrosion as you then have the whole length of copper pipe electrically connected to the hull. This is a very large mass of copper...
I was surprised/shocked at the use of copper as well.

But then I started wondering what material they could use in Germany in the late 70's or early 80s? Was PVC pipe available in Germany in that time frame? I have no idea. The boat owner was a very smart man and very experienced sailor so I would guess he looked at his options and picked the best choice available.

Flip side is that the copper did work and they would not have had a problem if the pipe had not leaked. I was more shocked that water leaking from a copper pipe would cause a problem on aluminum. No way would I have thought that possible.

Later,
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Old 20-10-2015, 09:19   #23
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Re: Advice on Aluminum boat Valencin 39, 1985

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Flip side is that the copper did work and they would not have had a problem if the pipe had not leaked. I was more shocked that water leaking from a copper pipe would cause a problem on aluminum. No way would I have thought that possible.

Later,
Dan
The water itself would not cause any problems. Marine aluminium is inert in seawater and does not require any protective coating.

However if you electrically connect the copper to the aluminium (by allowing the two touch) in the presence of water (an electrolyte) and oxygen, you will get serious corrosion. This is especially true with a large mass of copper. You can remove any potential for corrosion by isolating the electrical contact, by say coating the copper in plastic, or remove the moisture, but the latter is always going to optimistic in a boat. Not using copper water pipe is much more sensible.

This is just very basic stuff. Boatbuilders used to dealing with aluminium don't usually get these basics wrong, but it does happen. Sometimes owners commissioning the yacht insist on stupid ideas. Sometimes a respected yard that is used to dealing with aluminium will construct the hull, but the fit out is performed by a local boatyard that is accustomed to fibreglass boats. Sometimes extras are added that cause the problems.

It is a pity since if you remove these stupid decisions, aluminium is a great and very trouble free boatbuilding material.
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Old 20-10-2015, 09:28   #24
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Re: Advice on Aluminum boat Valencin 39, 1985

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The water itself would not cause any problems. Marine aluminium is inert in seawater and does not require any protective coating.
...
I agree with what I snipped out.

The corrosion that was seen was from leaky fresh water from the copper supply lines. The copper pipe did NOT touch the areas of corrosion but the water dripped from the pipes to the aluminum. The fresh water picked up enough copper to cause a problem. It took the yard that was working on the boat, which was about 20is years old at that point, quite some time to figure out the source of corrosion.

This was reported in Professional Boat Builder magazine.

Later,
Dan
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Old 20-10-2015, 09:57   #25
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Re: Advice on Aluminum boat Valencin 39, 1985

Thanks Dan.

Do you remember the issue of Professional Boatbuilder? I would love to read more, although I have no plans for copper water pipe .

Owning an aluminium boat you need to understand the issues that can lead to problems.
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Old 20-10-2015, 10:37   #26
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Re: Advice on Aluminum boat Valencin 39, 1985

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Thanks Dan.

Do you remember the issue of Professional Boatbuilder? I would love to read more, although I have no plans for copper water pipe .

Owning an aluminium boat you need to understand the issues that can lead to problems.
Why, yes, yes I do.

The boat was the Palawan VI and it, or a sister boat, is mentioned in Skene.

The article is in Professional Boat Builder issue 82, which is the April/May 2003 magazine. The article is on page 40 and they start discussing the use of copper allow hardware on page 44. Page 46 has the discussion about the leaking pipe along with a rather horrible photo of the corrosion.

Quote:
Some aluminum plating, particularly atop the aft fuel tank, showed heavy corrosion. Initially, the cause of the corrosion in this and a few other areas was a mystery, as there was no obvious direct contact with copper alloy. We eventually found the cause to be water, laden with salts of copper, dripping from a copper pipe above the damage areas. All these copper-alloy gremlins conspired to attack the aluminum hull and tank plating in several locations throughout the vessel.
I had to actually type in that quote since the file would not allow me to cut and paste. I think it typed it accurately.

I do not understand why aluminum boats do not paint the hull interior or at least the bilge. In theory, insulation would protect the hull above the bilge but I sure would be more comfortable with having everything painted as should be done in a steel boat. I don't see a down side and the paint would minimize/prevent any problems if a stray piece of metal found its way to the hull.

Later,
Dan
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Old 20-10-2015, 11:34   #27
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Re: Advice on Aluminum boat Valencin 39, 1985

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Why, yes, yes I do.

The boat was the Palawan VI and it, or a sister boat, is mentioned in Skene.

The article is in Professional Boat Builder issue 82, which is the April/May 2003 magazine. The article is on page 40 and they start discussing the use of copper allow hardware on page 44. Page 46 has the discussion about the leaking pipe along with a rather horrible photo of the corrosion.



I had to actually type in that quote since the file would not allow me to cut and paste. I think it typed it accurately.

I do not understand why aluminum boats do not paint the hull interior or at least the bilge. In theory, insulation would protect the hull above the bilge but I sure would be more comfortable with having everything painted as should be done in a steel boat. I don't see a down side and the paint would minimize/prevent any problems if a stray piece of metal found its way to the hull.

Later,
Dan
Aluminum boats are notorious for not holding paint well. My friends 48 foot custom built cutter was painted 3 times in 10 years. In the bilge, painting would likely be the worst case scenario...
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Old 21-10-2015, 06:24   #28
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Re: Advice on Aluminum boat Valencin 39, 1985

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Well what a hell, called a seller and arranged test sailing for couple of hours this Saturday.
If all goes well, will do the offer (with condition if it will pass a proper survey).
Good luck brother!

I hope it passes all the xslim tests!

PS It would be wise to share the survey findings if you end up going there...
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Old 21-10-2015, 06:37   #29
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Re: Advice on Aluminum boat Valencin 39, 1985

Hey guys!
thank you all for replies!

Any advice on what to look for during the sea-trial?
She's a narrow boat, 12m x 3.9m, but still, is it a problem to have a tiller on a 40ft boat?

Also, any advice on price negotiation? now the seller wants 59k. If all is good during the trial, should I propose 40 or 45 and start from there?

Thx!
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Old 21-10-2015, 06:52   #30
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Re: Advice on Aluminum boat Valencin 39, 1985

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Hey guys!
thank you all for replies!

Any advice on what to look for during the sea-trial?
She's a narrow boat, 12m x 3.9m, but still, is it a problem to have a tiller on a 40ft boat?

Also, any advice on price negotiation? now the seller wants 59k. If all is good during the trial, should I propose 40 or 45 and start from there?

Thx!
Do a search for surveys here... There's a few VERY good checklists... That will help you on the sail, and also help decide if you're willing to pay good money for a survey...

The tiller should not be a problem if the boat is an "easy balancer" and there's good rudder balance...

I think if you're willing to pay 50k, and you like everything thus far.... It's probably worth a survey... You can assume the seller "might" come down to that....

It's the survey itself that helps negotiating... Maybe he'll find 10-20k at professional refit prices that you can do for 5k... Then start the offer at 40k....
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