How coman is this -sinking boat

[[2068]]

That particular boat was left on it's mooring for a few seasons with an "electrical problem", and then hauled out into a yard in Florida.

As that dissolving photo is distressing me slightly, here is a picture of the outdrives on FlowerPower, taken pre-launch earlier this season:
(boat & drives are 10 yrs old, kept in salt water 9mths out of 12)

 

[RobWales]

That particular boat was left on it's mooring for a few seasons with an "electrical problem", and then hauled out into a yard in Florida.

As that dissolving photo is distressing me slightly, here is a picture of the outdrives on FlowerPower, taken pre-launch earlier this season:
(boat & drives are 10 yrs old, kept in salt water 9mths out of 12)

Nice and clean and in superb condition FP, also good to see that you observe the 1"clearance between the antifoul and the drives as many don't.

 

[DAKA]

I doubt a shaft boat would have fared much better - presumably the shafts would also dissolve?

In the old days shafts were steel and propellers bronze

They would have created an electrical circuit and corroded each other away and been a problem.


Most British built quality boats (under 25 years) now have specialist metal prop shafts and specialist metal props / p brackets

Their galvanic electrical reaction rates are almost identical so they are happy attached to one another or side by side without a current being made, they shouldnt dissolve one another.

 

[DAKA]

a leaking shaft seal is a scary thing. Happened to me on my current boat when at sea and the water ingress was worse than that. Somewhat surprised to see that the leaking seal here

Im interested in your leak Mike, theoretically any hole (excludes forward facing scoops) should act as a self bailer while underway 5knots +

could it have been your shaft seal coolant hose that was pressuring water in or where you stationary at the time ?

 

[Deleted User YDKXO]

Im interested in your leak Mike, theoretically any hole (excludes forward facing scoops) should act as a self bailer while underway 5knots +

could it have been your shaft seal coolant hose that was pressuring water in or where you stationary at the time ?

We were travelling at 20kts and the first thing I noticed was the high water bilge alarm going off. When I went down into the engine bay I nearly had a heart attack because water was spewing out of the starboard shaft seal. I stopped the boat immediately of course but water was still leaking in at a high rate. My boat is fitted with Deep Sea shaft seals as standard and they are a really terrible design IMHO. The sealing relies on 2 components butted up against each other, a fixed seat on the stern tube and a rotating seal on the propshaft, and the only thing stopping those 2 components coming apart are the hose clamps fixing those components. In the case of my seal, the hose clamps on the propshaft had loosened allowing the seal to move away from the seat and for seawater to pass through the gap. I managed to push the seal against the seat and tighten up the clamps but water was still leaking through. When I got the boat back to the marina, I had it lifted immediately and both seals changed. To answer your question, I thought it might be the flushing water leaking but the flow from the leak was far greater than the flow of flushing water.
Over the following winter, I changed the seals again for a pair of Tides seals, following advice on this forum, which IMHO are a much safer design and have the additional benefit of not requiring the boat to be lifted for the sealing component to be changed

 

[DAKA]

Thanks for the detail, scary !

Too late now I assume , I dont suppose you recall if the leaking water was warm ?
which would give an indication if it was the shaft coolant hose .

Cant see how water can back flow in a hole @ 5knots never mind 20 knots

(sounds like it did, I'm just struggling with the physics of it,
unless there is an eddy current formed by the tunnel but I would have expected that to draw well.)

 

[Deleted User YDKXO]

Thanks for the detail, scary !

Too late now I assume , I dont suppose you recall if the leaking water was warm ?
which would give an indication if it was the shaft coolant hose .

Cant see how water can back flow in a hole @ 5knots never mind 20 knots

(sounds like it did, I'm just struggling with the physics of it,
unless there is an eddy current formed by the tunnel but I would have expected that to draw well.)

This sounds like its going to start yet another argument about physics Firstly my boat doesn't have prop tunnels so the end of the stern tube is exposed to the flow of water under the hull but I'm not sure thats relevant anyway. I guess the pressure of the water at a depth of 1-1.5m, even at speed, is sufficient to force water back up the stern tube and yes, there may be some back eddy effects too

 

[DAKA]

Perhaps its a draft thing, mine is a lot less than 1.5m
About 1m , my head (seacock at bottom midships of hull) starts to suck at about 6 knots. @ 24 cruise its like a vacuum cleaner .

I suppose when on the plane the draft of the seacock my be less than 1m.

 

[rbcoomer]

In the old days shafts were steel and propellers bronze

They would have created an electrical circuit and corroded each other away and been a problem.


Most British built quality boats (under 25 years) now have specialist metal prop shafts and specialist metal props / p brackets

Their galvanic electrical reaction rates are almost identical so they are happy attached to one another or side by side without a current being made, they shouldnt dissolve one another.

Ok, accept that What about stray currents from other vessels? Are they alloys that are minimally reactive or just matched within their own setting. Not being obstinate, just curious as I've never had a boat on shafts and mine is recovered daily anyway (trailered) so nothing dissolves...

 

[gravygraham]

So what's the deal with the 1' un-antifouled strip round the drives?

 

[[2068]]

It's not a good idea to let copper-based antifouling get too close to an Aluminium outdrive.

 

[rosssavage]

So what's the deal with the 1' un-antifouled strip round the drives?

Looks more like 1" to me...