underwater flushing

tcwozere · 03 September 2004, 09:43

Hi,

First off, a quick thank you to the members here..

I bought an Avon 4m Searider a couple of weeks ago.. Just before I got it, Stuart over at Saxon Wharf suggested this place as an ideal point of reference, and since then I have managed to avoid making a load of faux pas's. I have also managed to convince myself that a 5.4m Rib would be a nice Christmas present from the wife..

As for the query, my rib is moored, (95% of the year), at Royal Clarence Marina in Gosport.. It is only coming ashore for periods of maintenance, diddling etc.. (They have no slip, and the public slips in Gosport are tide restricted). I thought this would make it a lot easier to go out for a tootle any time I wanted.. Plus with two young girls, launching and recovery seemed the harder option..

However, various threads here recommend flushing through after every use, and as I don't really want to take the rib out of the water every time, I was wondering if I could attach a pair of muff's, and flush it through with freshwater whilst the rib is moored at the marina.

Thanks,

slimtim · 03 September 2004, 09:47

Never done it, neither have I heard of anyone doing it but I guess if you can raise your engine high enough for the water intakes to be clear of the water then I guess there is no reason why you can't do it.

Someone may correct me though!

Well done on you purchase.

Hope that helps.

Tim

ashbypower · 03 September 2004, 09:55

Hi Tony and welcome. What O/B do you have, as some have a water inlet which is blanked off. You can remove this blanking plug connect up and adaptor to a hose and Bob's yer Mothers brother!!. We have this facility on our Yam's but must admit we've never used it.

Regards

Brian

MeMe · 03 September 2004, 09:55

........the engine was left down, in the water, would this not mean that the water would remain in the casing, through the exhaust and thus no salt crystals would form ?

MeMe · 03 September 2004, 09:58

Quote:

Originally Posted by ashbypower

You can remove this blanking plug connect up and adaptor to a hose

........you still be able to start the engine on the tilt so that the prop and inlets were out of the water. My Yam had the hose connection you mantion, however, this did not overide the usual inlets where one usually connecs the phones.

ashbypower · 03 September 2004, 10:08

Agree mate. However you by-pass the water pump therefore the water pressure from the hose helps flush out the coolant gallaries.
Your first point about leaving the engine down, I follow your logic but you must consider that salt water will remain in the powerhead and when dry will leave the Crystal deposits. Not wishing to teach mothers and egss etc

The main reason for fresh water flushing is to remove the salt water before deposits form.

All IMVHO of course,

Regards

Brian

tcwozere · 03 September 2004, 10:15

Thanks for the quick replies..

The engine is a mariner 30hp. I must confess I had hoped to leave the engine down, assuming that the muffs would only allow the freshwater into the intake. But if the engine can be flushed on the tilt, so much the better.. I am not sure what is meant by the "blanking plug", does this mean when flushing I would have to remove something prior to attaching the muffs and hose??

MeMe · 03 September 2004, 10:16

Quote:

Originally Posted by ashbypower

However you by-pass the water pump therefore the water presure from the hose helps flush out the coolant gallaries. Consider that salt water will remain in the powerhead and when dry will leave the Crystal deposits. Not wishing to teach mothers and egss etc

..........know this. Anyway, never been too good at sucking eggs, usually pay someone to do it for me. That said, I'm a pretty good pheasant plucker !

ashbypower · 03 September 2004, 10:19

Quote:

Originally Posted by tcwozere

Thanks for the quick replies..

The engine is a mariner 30hp. I must confess I had hoped to leave the engine down, assuming that the muffs would only allow the freshwater into the intake. But if the engine can be flushed on the tilt, so much the better.. I am not sure what is meant by the "blanking plug", does this mean when flucsing I would have to remove something prior to attaching the muffs and hose??

NO if flushing using Muffs the plug remain in. I'm unsure if your engine is fitted with such a device. It would be mounted somewhere on the "Leg" normally between the lowerpart of the powerhead and the gearbox.
And looks similar to the gearbox filler plug.

DO NOT USE THE GEARBOX PLUG!!!

Regards

Brian

ashbypower · 03 September 2004, 10:21

Quote:

Originally Posted by MeMe

..........know this. Anyway, never been too good at sucking eggs, usually pay someone to do it for me. That said, I'm a pretty good pheasant plucker !

Great news for you then!! the Pleasant season is not far away now so your gonnabe busy

Brian

slimtim · 03 September 2004, 10:25

Thinking about it you probably could do it with the engine down. Fit the muffs, then lower the engine and start her up after turning the hose on. The engine will suck out the last of the salt water and would hopefully pull the muffs in tight so no sea water was sucked in (only fresh water from the hose). You couldn't be sure that sea water wasn't drawn in though.

Tim

The Jackeens · 03 September 2004, 10:42

Thought it was my age

Missus

Matt · 03 September 2004, 11:44

I was under the impression that salt crystals are not the problem (this and the other flushing thread), since they'll wash out or dissolve the next time anyway (unless you are in saturated salt water), but flushing is for corrosion protection. Leaving saltwater in the aluminum engine encourages it to dissolve into a pile of aluminium oxide. The crystals referred to, I suspect, are alumium oxide (al203 I think), not salt, and that's why they don't dissolve, I failed chemistry a-level, but I do seem to remember aluminium oxide being particularly insoluble.

Engines these days do seem to be much better at resisting corrosion than years ago, but always flushing with fresh water is just good practice. Hopefully this engine has an external flushing connection as many of them seem to these days.
Either way, make sure all your anodes are, and remain, in good condition, and raise the engine clear of the water when not in use.
Cheers
M

Scary Des · 03 September 2004, 12:10

http://www.boatworld.co.uk/site1/pro...&pid=431&lv=91

Been discussed before but looks like a good option for an outboard. Could probably use underwater.

Another idea I have seen is a canvas bag/bucket that goes under the leg and hooks onto the transom while the boat is in the water, you then fill this bag with fresh water, I think it was aimed at keeping weed of the propellers but would allow you to flush with the outboard vertical.

Des

tue · 03 September 2004, 19:19

The problem is you can't really run the engine when it is fully tilted up. The way the cooling passages run water would find its way back through the exhaust and into the cylinders. If its on a mooring I wouldn't worry about flushing. Leave the engine down which will prevent crystal build up in the water pump. If you use it often enough then crystal build in the water passages won't cause a problem.

BTW. Your motor probably doesn't have any flush plug for the powerhaed.

tcwozere · 03 September 2004, 21:08

Hopefully it will be used regularly in Portsmouth harbour, even if it's just to get away from work..

I flushed the engine on dry land this afternoon, just so I could see what I was doing.. Instead of hanging over the transom wondering what was where.. and where was what..

Thanks again for the replies and link..