Mahogany hull in freshwater

[joegriffin]

I've been getting different advice about purchasing a mahogany double skin hulled cruiser to be used in fresh water. The boat in question is an Osborne Kestrel made in England in 1960. She has spent a good number of yers in sea water but I would want to use her mainly in Irish inland waters (The Shannon). I would occassionaly use her in coastal water but not very often

Any views?

[ishmael]

No problem. What is the contrary advice?

[dasboat]

Cannot imagine why someone would advise you that way.Were they referring to the fact she is wood,or to her condition or construction or something?
Das

[Dale Harvey]

I belive that the thinking is that the double skin construction may rot from the center out when the salt is leached out by freshwater. Depending upon what the materials are between the plank layers, this could be a very valid concern. Consult a surveyor or restoration expert that has experiance with this particular make of vessel.

[joegriffin]

Some people are warning me not to get a boat wiht a mahogany hull as this will rot in fresh water but is OK in salt water. Other advice says this is not a problem. Further advice says that if the boat was originally kept in sea water then the hull will now be 'pickled' and there won't be a problem.

Enough to confuse a beginner like me!

Originally posted by ishmael:
No problem. What is the contrary advice?

[ishmael]

I hadn't considered the peculiarities of double planking, but I still don't think it would be a problem. I doubt there is anything between the layers which would suddenly rot upon the switch from salt to fresh. Note I say 'think' and 'doubt'. It wouldn't hurt, as Dale suggests, to consult with someone who knows this boat's construction.

[Art Read]

The "salt as a preservative" debate has been kicked around a good bit here. The gist of it seems to be that, A: It's an old wives tale... Rot spores need a specific range of temperature and humididy to form and that virtually no wood that is either fully immersed or properly ventilated will tend to rot. Damage in boats used either in salt water or fresh is usually attributable to improper weatherproofing against rain above decks or improper ventilation while in storage creating a rot-friendly moist, humid environment. Or, B: Boats used in salt water are somehow "pickled" against rot.

I've never seen any "scientific" explaination that proves salt "pickled" wood is impervious to rot, but there are lot's of examples of boats of quite respactable age who's owners claim it's the salt that saved them. One even explained his Baltic Trader's longevity with fact that she was origanally used to haul cargos of salt! On the other hand, some of oldest known specimens of wood known come from deep under cold fresh water lakes. Go figure. Bottom line, I suspect it's far more important to keep the boat properly finished, prevent fresh water leaks on deck and provide plenty of positive ventilation in all the nooks and hidy holes aboard than what type of water you sail her in.

[PugetSound]

A few of points are in order here:

- Saltwater does not prevent rot quite so much as it provides a hostile environment to rot. There is a difference.
- The cold water at the bottom of the Great Lakes is not conducive to rot for a couple of reasons. First it is really really cold. Fungus spores can survive cold but they don't thrive. Second, any time you start talking about deep water and living things you need to consider that oxygen concentration varies with depth. The degree of variation is significant enough to affect corrosion rates so I imagine it will also affect fungus.
- Double planked hulls that are not maintained may very well develop pockets of trouble between plank layers but so what? Neglect anything and you'll likely find out just how biodegradable it is. The solution is obvious. Maintain the boat and it becomes a non issue.
- OK now, help me out here guys; we're talking about a boat which is already over 40 years old (and presumably in good shape) and has spent most of it's life in Ireland. From what I remember about my granddad's hometown (halfway between Galway and Tuam), it rains alot in Ireland. It rains a whole hell-of-a lot in Ireland -kinda like the Northwest USA. So why be concerned about whether the boat gets rained on while it sits in salt water or fresh?

Joe, if it is the boat for you, then buy it and go sailing on the river Shannon and enjoy yourself. If you don't plan on selling the boat in your lifetime then I would advise you to put it in your will because, fresh water or salt, that boat will likely outlive you.

[joegriffin]

Thanks to all of you for the advice. It has been really helpful. I can now continue seraching for the boat of my dreams wiht a bit more confidence.

If any of you are ever over this way then be sure to let me know and we can get together and do a bit of boating in whatever boat I happen to have at the time.


Originally posted by PugetSound:
A few of points are in order here:

- Saltwater does not prevent rot quite so much as it provides a hostile environment to rot. There is a difference.
- The cold water at the bottom of the Great Lakes is not conducive to rot for a couple of reasons. First it is really really cold. Fungus spores can survive cold but they don't thrive. Second, any time you start talking about deep water and living things you need to consider that oxygen concentration varies with depth. The degree of variation is significant enough to affect corrosion rates so I imagine it will also affect fungus.
- Double planked hulls that are not maintained may very well develop pockets of trouble between plank layers but so what? Neglect anything and you'll likely find out just how biodegradable it is. The solution is obvious. Maintain the boat and it becomes a non issue.
- OK now, help me out here guys; we're talking about a boat which is already over 40 years old (and presumably in good shape) and has spent most of it's life in Ireland. From what I remember about my granddad's hometown (halfway between Galway and Tuam), it rains alot in Ireland. It rains a whole hell-of-a lot in Ireland -kinda like the Northwest USA. So why be concerned about whether the boat gets rained on while it sits in salt water or fresh?

Joe, if it is the boat for you, then buy it and go sailing on the river Shannon and enjoy yourself. If you don't plan on selling the boat in your lifetime then I would advise you to put it in your will because, fresh water or salt, that boat will likely outlive you.

[castletine]

Joe

Point of interest for you is that William Osborne Ltd still survives and is still operating out of Littlehampton.

One of the former guardians of my Osborne Motor Yacht had been in touch and had met the Grandson of the man who originally built my Yacht in 1931!! Priceless stuff.

Regards

Jonathan