River rot?

[L124C]

A long time ago, I was having a boat surveyed. The Surveyor found some rot at the base of a bulkhead, and asked if the boat had spent a lot of time in the Delta (fresh water). In fact, it had. I asked him how he knew that (the boat was currently docked in salt water). He said "We call this river rot. We only see it in boats that have spent a lot of time in fresh water". I thought his observation was interesting.
Having learned a lot since, I ask what is now an obvious question. Why would the type of water the boat was in affect the interior (unless the boat had sunk, of course)? Couldn't this condition be produced by rain water from leaking partners at the mast (as one of many examples)? Anybody heard of River Rot?

[tommays]

In fact if you read the fine print many new boats are not covered for rain water dammage

[CaptainForce]

You might recall from historical accounts that, before refrigeration, foods were often preserved in salt or brine. Those same microbes that spoil food are similar to those that cause the decay of wood. 'take care and joy, Aythya crew

[L124C]

Originally Posted by CaptainForce

You might recall from historical accounts that, before refrigeration, foods were often preserved in salt or brine. Those same microbes that spoil food are similar to those that cause the decay of wood. 'take care and joy, Aythya crew

I'm not clear on your point, but think you are supporting the Surveyors theory. Being a diver and windsurfer, I know for example, that salt water on a wet suit or sail, takes forever to dry. However, unlike fresh water, it will not create mildew, if not afforded proper ventilation to dry out. I'm also a Carpenter and understand the process of moisture and wood rot. However, I still don't understand how the interior of a boat could react differently to the type of water the boat is sailed in (Bilge not withstanding, of course). Now...If the boat had been submerged and re-floated, that's another matter. However, I don't think I would want the boat in either case!

[pedcab]

Hi

I keep my 40+ yr old Piver Nugget in a swinging mooring way up Tejo River in Portugal, floating in fresh water all year being, as such, an easy target for the so called "river rot".

I believe that the explanation for this phenomena is easy to decipher: Wood in fresh water rots faster than when in sea water due to the absence of salt, which is known for ages as, for instance, a food preservative which fights the presece of moisture and gives micro-organisms an unfriendly environment to live in.

Out of curiosity, the old sailors of this river, who used to carry arround freights of wine, cork, rice, sand, wood, hay, etc in huge sailing boats used to compete amongst themselves for the rare chance of loading salt freights, and they never missed a chance of, when sailing down to Lisbon, get some gallons of salt water inside the boat to preserve the wood, generally made out of pine, pitch pine or spruce planking over oak framing. In fact, the boats working in Lisbon (as people carriers from margin to margin) and, consequently in salt water all year, lasted AGES longer than those working mainly further upriver in fresh water.

Here's one of those boats called "Fragatas" (Frigates):



One more thing, river or otherwise rot happens faster in woods that are allowed to go throught repeated cycles of wet and dry. Wood that is permanently submerged takes forever to rot. In fact, boat building wood logs used to be stored underwater because that way, or so the older boat builders claim, they would last longer and retrieve longer lasting planks than if stored outside exposed to rain and sun.


Regards

Pedro Cabral

[bartvdv]

So if we follow the same arguments, we should treat our exterior woodwork (e.g. cockpit gratings) with salt water ?....

[pedcab]

That's the theory that's been working for us for ages... A couple of buckets of sea water every once in a while will help prevent rot in exposed woods...

[christyleigh]

Originally Posted by pedcab

That's the theory that's been working for us for ages... A couple of buckets of sea water every once in a while will help prevent rot in exposed woods...

The only problem is that when you are splashing that salt water around - keep it off your metals. Salt water on metal basically Never Dries.... the salt just sits there absorbing moisture from the air and rusting your metals - yes even stainless. That's why you always hear that "Fresh Water" boats are so much better/longer lived, but as usual there are two sides to the coin as the main topic of this thread shows.

[L124C]

Originally Posted by pedcab

I believe that the explanation for this phenomena is easy to decipher: Wood in fresh water rots faster than when in sea water due to the absence of salt, which is known for ages as, for instance, a food preservative which fights the presece of moisture and gives micro-organisms an unfriendly environment to live in.

Interesting. However, the interior surfaces ideally will not be "in salt water". So, I have to assume that if there is a leak that is allowing an interior surface to get wet (as there always seems to be in a 30 year old boat), a boat in salt water is likely to allow salt water in sometimes, thereby occasionally treating the wood. Pretty amazing, considering that in the example of the leaking partners I gave (which I think was probably the source in the surveyed boat), the amount of salt water coming in, is going to be proportionately much less than fresh. On my boat, I have to be in pretty big seas before the partners would get wet with salt water, yet I rinse the boat off with fresh water every time I sail. Not to mention rain. Well, I got my answer, RIVER ROT LIVES! Funny...as long as I've been on this forum, it still surprises me when I find out I'm communicating with sailors from Portugal, Singapore, etc. Gotta love it!

[L124C]

Originally Posted by christyleigh

That's why you always hear that "Fresh Water" boats are so much better/longer lived, but as usual there are two sides to the coin as the main topic of this thread shows.

In fact, I was responding to another thread on that very topic with my surveyor story. I started to write my response, and suddenly thought, "Wait...that doesn't make any sense. Better look into this". Hence...this thread! An example of how thought provoking these forums can be.