To flush or not to flush...

[Bjohnson]

Gearing up for the new season and had some potential bad news today that my usual storage and self launch facility may not be available this year. I base my rib out of Dartmouth and there aren’t any other (viable) options for me, so now I’m seriously considering a permanent mooring on the river and purchasing a versadock (type) floating dock for my rib.

I’m usually meticulous with cleaning down my boat and flushing the engine - a 225 Mercury 2 stroke optimax.

So my question - if i end up leaving the rib on a floating dock throughout the season, will it be a write off if I don’t flush it?

I should also say, the mooring I’ve been offered is mid river, so no access to fresh water.

[Salty Pete]

Good question and I am going to have a go at guessing the correct answer.

I'm sure I will be advised if I'm talking rubbish. (Since I normally do)

There are plenty of boats moored in salt water so it can't be a all that important.

When you bring your boat home on a trailer, the water drains out of it and is replaced by air, an element required for oxidisation. So, you flush it with fresh water.

If the outboard is left in the water, the air can't get in hence, oxidisation won't be a problem.

Galvanic action will be, but the anodes attached to the motor should reduce this problem, of course keeping your eye on the anodes is important.

How good is my guess?

[jonp]

Many commercial outboards are never flushed but the fact they are run daily helps reduce the effects of salt drying and building up in the engines.

I recently bought an outboard (Suzuki 140 ) with jut 235 hrs which was chocker block with salt. The anodes had been changed twice in those 235 hrs yet they were totally gone when I bought the engine. No water pumped as the cooling system was totally blocked, as was the thermostat. This engine had been flushed using the flush ports but not using the muffs for a full cooling system flush (something many don't realise doesn't totally flush the engine fully).

[Salty Pete]

Originally Posted by jonp

Many commercial outboards are never flushed but the fact they are run daily helps reduce the effects of salt drying and building up in the engines.

I recently bought an outboard (Suzuki 140 ) with jut 235 hrs which was chocker block with salt. The anodes had been changed twice in those 235 hrs yet they were totally gone when I bought the engine. No water pumped as the cooling system was totally blocked, as was the thermostat. This engine had been flushed using the flush ports but not using the muffs for a full cooling system flush (something many don't realise doesn't totally flush the engine fully).

Interesting jonp, when I bought my engine new, the dealer told me the preferred way to flush the engine was via the flush plug and not muffs.

However 2 years after I had bought the engine I read the manual (the standard time to read the manual after purchase) and it recommended flushing the engine with muffs.

I guess I need to change.

[treerat]

5l hozelock pump container, fill with fresh water and push in via the flush points, not as good as a muff wash, but better then nothing?

[lakelandterrier]

How well will a drive on dock work on swinging mooring? - most I know of are moored to a pontoon to hold them straight when driving on.

Also most moorings in the Dart are now trots - not swinging - which wouldn't work for a drive on dock at all.

There's a long waiting list for river moorings.

You'll also need a tender of some kind the reach the mooring, and find somewhere to keep it. Parking in Dartmouth / Kingswear is also a nightmare as I'm sure you know.

Have you considered Dartside at Galmpton? - but you'll be limited to +/- c.2.5-3 hours HW.

Alternatively consider putting the dock on a marina berth - will have fresh water. It won't be cheap, but will give you quick & easy access from shore to water and not be tide dependent.

[Fender]

Originally Posted by Bjohnson

Gearing up for the new season and had some potential bad news today that my usual storage and self launch facility may not be available this year. I base my rib out of Dartmouth and there aren’t any other (viable) options for me, so now I’m seriously considering a permanent mooring on the river and purchasing a versadock (type) floating dock for my rib.

I’m usually meticulous with cleaning down my boat and flushing the engine - a 225 Mercury 2 stroke optimax.

So my question - if i end up leaving the rib on a floating dock throughout the season, will it be a write off if I don’t flush it?

I should also say, the mooring I’ve been offered is mid river, so no access to fresh water.

Unless the floaty dock is fixed to a pontoon its an't going to work

[36valley]

Originally Posted by Fender

Unless the floaty dock is fixed to a pontoon its an't going to work

It is possible to use one on a mooring, but not without some issues. It would need two mooring points to stop it moving to much when trying to get back on.

Tetradock have a photo of one of there's on a Trot mooring at Fowey. But you would need to have an end mooring for it to work with any degree of ease.

I use one with a reasonably heavy rib and find that if I drive on just a bit too far then I sometimes have to give it a bit of a push backwards before I can reverse off without reving the engine too much. That's not much of an issue when you've got a pontoon to brace against but might prove difficult mid river.

I also need an air bag/block to get the stern clear of the water at rest and then lower it to make getting off easier. Getting access to the air hose is again easy from a pontoon, not so much of you had to reach from the boat.

[Fender]

Originally Posted by 36valley

It is possible to use one on a mooring, but not without some issues. It would need two mooring points to stop it moving to much when trying to get back on.

What about the rest of the river moorings swinging with the stream and wind?

Tetradock have a photo of one of there's on a Trot mooring at Fowey. But you would need to have an end mooring for it to work with any degree of ease.
Also with the slack in the mooring to compensate for tide height changes you'll just keep pushing the dock away from the bow of the rib then the dock will twist under the load and screw the attempt up??

I use one with a reasonably heavy rib and find that if I drive on just a bit too far then I sometimes have to give it a bit of a push backwards before I can reverse off without reving the engine too much. That's not much of an issue when you've got a pontoon to brace against but might prove difficult mid river.
Yes!

I also need an air bag/block to get the stern clear of the water at rest and then lower it to make getting off easier. Getting access to the air hose is again easy from a pontoon, not so much of you had to reach from the boat.

Love to see someone try to mount a boat on a moving floaty dock - be quiet entertaining

[jeffstevens763@g]

you can buy a flush bag lift engine fit bag lower fill with fresh water run job done

[36valley]

As I said "not without some issues" .

[Bjohnson]

Thanks for the replies.

I spoke with a friend who has twin 225 Optis on a bigger cabin cruiser that’s left afloat through the summer, he’s jury rigged a hose system off his transom shower and flushes from his onboard freshwater tanks after each use - no good for my rib!

Spoke with another contact who used to keep their fishing boat on a floating dock mid river, they jury rigged a large plastic freshwater tank on the pontoon/dock and used a 12V battery to pump fresh water from the tank to flush the outboard.

I also spoke with a Mercury service place and they said it might not be a massive issue not to flush (through the summer) given the waterways on a 3l V6 are pretty big (his point being compared to a small outboard engine with small waterways which may fur up more quickly if not regularly flushed). Not sure I’m entirely happy with that approach.

Another option could be to buy a flushing bag, hook it over the outboard, fill with fresh water (from a portable jerry can/container left on the pontoon), to flush. I can see this might work but probably needs testing to prove the concept!

I’m still awaiting confirmation of mooring availability, so this may all yet be a moot point!

Also to clarify the above exchanges, my option is a mid river pontoon, against which i can moor a floating dock, so hopefully no chance of the dock running away as we try to mount it!!!

[Poly]

Originally Posted by Salty Pete

Good question and I am going to have a go at guessing the correct answer.

I'm sure I will be advised if I'm talking rubbish. (Since I normally do)

There are plenty of boats moored in salt water so it can't be a all that important.

When you bring your boat home on a trailer, the water drains out of it and is replaced by air, an element required for oxidisation. So, you flush it with fresh water.

If the outboard is left in the water, the air can't get in hence, oxidisation won't be a problem.

Galvanic action will be, but the anodes attached to the motor should reduce this problem, of course keeping your eye on the anodes is important.

How good is my guess?

I think you are close - oxidation isn't really the problem - its the water evaporating and leaving the solid salt behind. If you leave it in the water with the leg down it will be hard to dry out like that. As JonP says regular use will help a lot too. If you were going to put it on a dock with engine leg up and leave if 3 weeks between use regularly I think you might gradually build up salt. I doubt it needs flushed every time though to get rid of the salt.

[Fergus3060]

I'll be keeping my Arctic on a swing mooring this year so following with interest as I've only ever trailered a boat before. Am I to understand that if you couldn't flush fairly regularly you'd leave the leg down to stop the water jacket drying out and therefore salt build up? I'd imagined that the water would drain down out of the water jacket to roughly the surface level, still leaving the opportunity for salt to gradually build up in the water channels above surface level?

[jwalker]

Originally Posted by Poly

....I doubt it needs flushed every time though to get rid of the salt.

Aye, I think it does. It's weird since salt is generally water soluble but outboad water channels clog up markedly with what appears to be insoluble salt. Perhaps it's soduimalumochloride or summat....I dunno but it's tricky to get rid of for sure.

Since salt is hygroscopic, if an outboard isn't flushed and lies above water where, by definition, humidity is high then I reckon the inside of a outboard will pretty much lie wet all the time.

[jakew009]

Originally Posted by Fender

Love to see someone try to mount a boat on a moving floaty dock - be quiet entertaining

I reckon I could do it with the perfect amount of speed on approach.

Not so fast that you fly straight over the top of the dock and off the other side.

But not so slow that the dock moves away rather than the boat jumping onto it.

About 12 knots should do it imo

[mikehhogg]

there are a lot of variables here, engine quality ie the actual grade of aluminium alloy the outboard\leg is made from. I have seen new honda outboards to dissolve in a season from the inside out. My personal experience is launching and mooring every year for the past fifteen years in may and taking out in october weather permitting. I flush when I get it home.its a yamaha v4 .engine is raised between use on the mooring .People could have different experiences with different water compositions ,Brackish estuaries can cause more problems

[Miss Guided]

Versadock or tetradock floating dock on a swinging mooring - DON'T. There'll be an accident.

I do agree with Mr Treerat for flushing! You need a good flushing

MGx

[willk]

Originally Posted by jakew009

I reckon I could do it with the perfect amount of speed on approach.

Not so fast that you fly straight over the top of the dock and off the other side.

But not so slow that the dock moves away rather than the boat jumping onto it.

About 12 knots should do it imo

...the first floating dock with an arrestor wire?

[Poly]

Originally Posted by jwalker

Aye, I think it does. It's weird since salt is generally water soluble but outboad water channels clog up markedly with what appears to be insoluble salt. Perhaps it's soduimalumochloride or summat....I dunno but it's tricky to get rid of for sure.

People report success flushing with weak acids - so its presumably calcium carbonate (scale like in English kettles and washing machines). That makes sense as the deposits are mostly in hot bits and CaCO3 has inverse solubility with temp (ie. it dissolves better, although still poorly, in cold water). It should get worse with use rather just a poor flushing regime then. The question is does keeping a boat afloat used at least once a week, and flushing once a month; using it every day and flushing at end of the season (perhaps with some proprietary treatment); or using it every few weeks and flushing it every night when you get home make a meaningful difference?