Log Impellor removal

jobbie

jobbie

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Do any of you remove your log impellor at the end of a trip to save it from fouling and then use an appropriate blanking cap? I went to fit mine the other day and found it quite daunting as this plume of ice cold water rushed in. I panicked and whacked the blanking cap back on, then spent about half an hour mopping up. Is there a knack to this that I'm missing?
 
No, I leave mine in position until it ceases to function and then remove and clean it. I try to avoid too much water entering the boat by placing a floor cloth over the opening quickly and then manipulating the cap on under the floor cloth.
 
I got quite paranoid about this at one stage. I made up a gadget out of old headlining with the foam scraped off (I had a Westerly at the time /forums/images/graemlins/smile.gif ) and cords which I could deploy over the bow and then slide back using the cords from each side of the boat until the piece of headlining was over the transducer. This will only work if the transducer is forward of the keel, of course. I had to add some weights to persuade the gadget to sink below the forefoot. It worked OK the one time I actually used it.
 
The amount that floods in looks worse than it is. I doubt if anybody ever sank their boat this way. Just pull it out with one hand, expect the fountain, and put the blanking cap on with the other hand. Don't faff about trying to control the flood.

On the other hand if you drop the blanking cap you are then free to panic.
 
Move to the med and at least its nice warm water!
I was once old of a method, cut a old car tyre inner tube to a length as long as your arm. Tie one end of this around the log fitting and hold the other end up.
Put your other arm down the hole and take out the log fitting. The tube fills up to water level and thats it.
Never tested myself but should work ok if your log fittings not deeper than the length of your arm, mind you then you have a tube of water to mop up!
 
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The amount that floods in looks worse than it is.


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agree: it is not a bad idea to (first check bilge pumps are ok) let water come in freely, take off the plug and just look at the quantity of water that flows; one is (at least I was) surprised at how long the plug has to be kept open until water quantity becomes noticeable

now I use that system every time I want to clean the bilge: pull off the log transducer, poke a chopstick inside to keep the safety flap open, let water in and wash the bilge; put the plug back on and pump out water

at least that gives confidence about bilge pumps /forums/images/graemlins/ooo.gif
 
It's easy to be confident after you've done it but it really isn't at all life-threatening!
If you still refuse to take our word for it then dry out your Cobra against a wall or on a beach before you experiment.
I won't even cross my fingers for you, it's a cinch.
 
I wouldn't trust the cap (NASA) to seal the hole for long periods. It doesn't seem as secure to me as the impeller with its O-ring.

I only remove the impeller to clean it and then I immediately replace it. It's important not to rush because it would be all to easy to cross the thread or otherwise damage the fitting and then you're stuffed!
 
It does require a "cool hand luke" touch, but the latest fittings have a closure that really dampens down the inrush - do you not have this, or are you still with the earlier gusher-type?
If so, worth buying a new tube and fitting it - an easy job.

PWG
 
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It does require a "cool hand luke" touch, but the latest fittings have a closure that really dampens down the inrush - do you not have this, or are you still with the earlier gusher-type?
If so, worth buying a new tube and fitting it - an easy job.

PWG

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It did seem to rush in with a bit of force ,which took me by surprise so I would say there doesn't appear to have a flap to stem the flow on the tube.The boats fitted with older ST50 instruments.
I think it makes sense to put the impellor in and leave it until it fouls. It seems alot of hassle removing it after every trip out.
 
We have a newish Beneteau and I was shown how to get the impeller unit out .. Undo the locking ring and move the impeller unit up and down 6 - 7 times to dislodge marine creatures etc .. Then remove .. Gush of water which subsides .. Replace with plug .. Clean Impeller and refit .. Get about a litre of water in .. /forums/images/graemlins/grin.gif
 
Put a couple of sponges on the 'floor' and they'll soak up most of the water that comes in. As said before, don't faff about, unscrew the impellor and swiftly pull out with left hand (if you're right-handed) followed immediately with blanking plate with right hand. With practice, there will only be a cup or two of water that the sponges don't get.
 
You can use one of those tapered wooden plugs to quickly plug the hole when the impeller unit comes out. ( You should have one on a string close by the unit anyway in case of emergencies). You have to be careful though, if you ram it in too hard it can damage or crack the fitting and that would be a <u>real</u> problem!
 
You could try taking the log out as you are going along, the scientists out there will be able to explain why, but if I remove the log when berthed quite a fountain comes in ! If the log is taken out when going along the water ingress is reduced hugely. Might be worth a try.
 
I only remove the log impeller when it has got bunged up with fouling. When I do, I use a sheet of fabric like a collision mat to cover the log before extracting the impeller. It consists of heavy water proof fabric about a foot square with a light line attached to each corner. It also has 2 heavy stiffeners (I used pieces of fibreglass batten; metal rod would be fine) along two opposite edges. The stiffeners are tied into the lines, leaving about 1/4" of line between stiffeners and fabric. When the boat is out of the water, locate the fabric over the impeller and fix the lines to suitable places on deck. I use the two midships mooring cleats and two stanchion bases further forward. Mark each line at an easily identified place. I tied cable ties to the lines where they cross the rubbing strake to mark them. Once this is all done, you can deploy the device over the log each time you want to remove it. It takes a little while to develop the knack of shuggling it back from the bow into place without getting things twisted. Even with the knack (3 years worth in my case) it still takes 5 minutes or so to rig up. But it works every time so far. The marks on the lines help to confirm that everything is in the right place.
I expect this can't be done with some configurations, e.g.if the log is between bilge keels or alongside a fin keel. My log is in front of the keel, where it works well.

Derek
 
I learned on this forum that if the impeller isn't working, its worth, while the boat is in motion, trying unscrewing it slightly, then turning the unit round through 180 degs and back a couple of times. This seems to free the paddle wheel of any weed or whatever that is stopping it running freely.

Works for me.
 
Yep - the first time I did it I was really nervous, now I am happy to do so when required - not too much water and I use it as an opportunity to clean the bilges!

Not scaremongering; but I am curious, has anyone had a catastrophic failure when removing/cleaning? Flaps completely failing?

If the cover idea works for you and gives you more confidence then fine - but how do you know if it is the cover working or just the flaps working correctly? Belt and braces I suppose!

I understand the logic of removing when in motion, but on my T34 I would probably be diced by the starboard engine if I tried it! /forums/images/graemlins/frown.gif
 
I have a technique that changes hands.
My left hand is useless for putting caps on etc. - I'm a completely right handed person. So I unscrew log holding ring till it's only just on a part turn on thread. I then have blanking cap in RIGHT hand and complete the removal of log with left hand. This means that BEST hand is putting cap on.

Some reckon that less than 1/2 litre comes in .. each time I'v done it I reckon 2 - 3 litres is more like it ! I fitted mine through hull in the heads compartment ... that way I'm keeping any water that comes in - in the right place !
 
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