tgalea
Member
Is it possible to lift a paddle wheel transducer (speed log) for maintenance while the boat is still in the water ? That is i mean without drowning it!
Thanks
Tyrone.
Thanks
Tyrone.
Lifting a paddle wheel transducer in the water
- Thread starter tgalea
- Start date
pvb
Well-known member
Easy....
Remember that the transducer is only about a foot below the waterline, so there's very little pressure. I find it's easiest to use a sponge to temporarily seal the hole before putting the blanking plug in. Difficult to gauge, but I reckon removing and replacing the transducer only results in about a gallon of water in the bilges.
Remember that you can antifoul the paddle wheel and its housing, to stop it bunging up with little creatures. You need to take the paddle wheel out of its housing first (tiny screwdrivers usually needed), give it all a light sanding, and then apply a thin coat of the sort of hard antifouling which is recommended for outdrive legs, etc.
Remember that the transducer is only about a foot below the waterline, so there's very little pressure. I find it's easiest to use a sponge to temporarily seal the hole before putting the blanking plug in. Difficult to gauge, but I reckon removing and replacing the transducer only results in about a gallon of water in the bilges.
Remember that you can antifoul the paddle wheel and its housing, to stop it bunging up with little creatures. You need to take the paddle wheel out of its housing first (tiny screwdrivers usually needed), give it all a light sanding, and then apply a thin coat of the sort of hard antifouling which is recommended for outdrive legs, etc.
charles_reed
Active member
Yes,
providing you have the blanking plug to put into the transducer socket.
Those made after about 1998, usually have a flap valve to reduce the amount of water getting in whilst you make the changeover between the two - I can clean the paddle wheel on mine and only get about 1/2 cupful of water in.
providing you have the blanking plug to put into the transducer socket.
Those made after about 1998, usually have a flap valve to reduce the amount of water getting in whilst you make the changeover between the two - I can clean the paddle wheel on mine and only get about 1/2 cupful of water in.
AuntyPodes
New member
Re: Easy....
Can't see the advantage of a sponge if you've a dummy - just bung the "dummy" transducer straight in. I antifoul mine, too. I remove the paddle, clean the housing and paddle and dip them in my standard (hard - racing type) a/foul - let them drain and dry - reassemble and replace. it. Incidentally, it pays to remove the transducer if you're being lifted in slings - otherwise you may lose a paddle blade or two. This happened to me - couldn't get a replacement - wound up fashioning a new blade out of one of those little lamp socket covers and epoxied it in place. It's been on twelve months and is indistinguishable from the other blades - works perfectly. It's called Kiwi ingenuity - but by birth I'm a pom - must be contagious!
Can't see the advantage of a sponge if you've a dummy - just bung the "dummy" transducer straight in. I antifoul mine, too. I remove the paddle, clean the housing and paddle and dip them in my standard (hard - racing type) a/foul - let them drain and dry - reassemble and replace. it. Incidentally, it pays to remove the transducer if you're being lifted in slings - otherwise you may lose a paddle blade or two. This happened to me - couldn't get a replacement - wound up fashioning a new blade out of one of those little lamp socket covers and epoxied it in place. It's been on twelve months and is indistinguishable from the other blades - works perfectly. It's called Kiwi ingenuity - but by birth I'm a pom - must be contagious!
hutch
New member
Re: Easy....
I would recommend that you take the transducer out whenever you are not using the boat - replacing it of course with the blanking plug! Saves lots of trouble in the long run .... Once you master the art of removal and replacement, the amount of water that gets into the boat is very small. You then don't need to antifoul the thing. A regular coating of vaseline acts as an antifouling, helps the seal, keeps the o-rings soft, lubricates the wheel bearings, etc. Also means that you don't leave it in accidentally when being lifted.
Another reason for removing it when not in use - I have seen a boat sunk as a result of a lightning strike blowing the transducer out. (But then the lightning also blew out the depth transducer as well as punching a large hole through the hull at the foot of the mast!)
I would recommend that you take the transducer out whenever you are not using the boat - replacing it of course with the blanking plug! Saves lots of trouble in the long run .... Once you master the art of removal and replacement, the amount of water that gets into the boat is very small. You then don't need to antifoul the thing. A regular coating of vaseline acts as an antifouling, helps the seal, keeps the o-rings soft, lubricates the wheel bearings, etc. Also means that you don't leave it in accidentally when being lifted.
Another reason for removing it when not in use - I have seen a boat sunk as a result of a lightning strike blowing the transducer out. (But then the lightning also blew out the depth transducer as well as punching a large hole through the hull at the foot of the mast!)
tgalea
Member
Re: Easy....
Read all the posts and thanks to all. My problem is that being my first season with a sailing boat i didn't antifoul the thing and initially had lots of growth on which got it stuck and read ZERO.
I then when in for a dip in the water and cleaned out the fouling and it worked again. Now the problem is that after a few weeks although the paddle wheel is free since i've tried it with my fingers i still get a ZERO reading.
Any ideas ?
Thanks
Tyrone.
Read all the posts and thanks to all. My problem is that being my first season with a sailing boat i didn't antifoul the thing and initially had lots of growth on which got it stuck and read ZERO.
I then when in for a dip in the water and cleaned out the fouling and it worked again. Now the problem is that after a few weeks although the paddle wheel is free since i've tried it with my fingers i still get a ZERO reading.
Any ideas ?
Thanks
Tyrone.
pvb
Well-known member
Sensitive adjustments...
Sometimes. although the paddle wheel appears to be free, there's too much friction for it to read the speed properly. You may need to make small adjustments to the axles the paddle spins on, to ensure it's spinning very freely.
If that doesn't work, take the paddle wheel out and look at it carefully. There should be a tiny magnet in the edge of one of the blades - this causes a pulse of electricity every time the paddle turns, and hence gives a speed reading. Sometimes, the magnet drops out, in which case the instrument will always show zero speed. Or, it could be a wiring failure. Or, it could be an instrument head failure - does the log still work even though the speed doesn't?
Sometimes. although the paddle wheel appears to be free, there's too much friction for it to read the speed properly. You may need to make small adjustments to the axles the paddle spins on, to ensure it's spinning very freely.
If that doesn't work, take the paddle wheel out and look at it carefully. There should be a tiny magnet in the edge of one of the blades - this causes a pulse of electricity every time the paddle turns, and hence gives a speed reading. Sometimes, the magnet drops out, in which case the instrument will always show zero speed. Or, it could be a wiring failure. Or, it could be an instrument head failure - does the log still work even though the speed doesn't?
Chris_Stannard
New member
Re: Easy....
It is important to ensure that the paddle wheel is in line with the keel. If your boat uses the same transducer as mine there is a little arrowhead on the log moulding which must be facing forward. If it is the wrong way round you may not get a reading. The test though is to take the transducer out, and spin it whilst someone watches the log, if it does not move the tranducer is faulty or you have a wiring problem.
Chris Stannard
It is important to ensure that the paddle wheel is in line with the keel. If your boat uses the same transducer as mine there is a little arrowhead on the log moulding which must be facing forward. If it is the wrong way round you may not get a reading. The test though is to take the transducer out, and spin it whilst someone watches the log, if it does not move the tranducer is faulty or you have a wiring problem.
Chris Stannard
oldharry
Well-known member
Re missing magnets
When the boat is being pressure washed after lifting, if the High pressure jet is directed directly on to the paddle wheel it will spin so fast that the tiny magnet can be thrown out. Without it of course the transducer gives no signal. Took me ages to work out what was wrong with the log.
Its said to be a favourite game with the yard boys when cleaning off - see how high a speed they can get the log to register with the pressure washer......
Cure is of course a replacement paddle wheel. An older transducer if the plastic gets damaged the water can get in and rust the magnet jamming it.
<P ID="edit"><FONT SIZE=-1>Edited by oldharry on 19/08/2002 08:22 (server time).</FONT></P>
When the boat is being pressure washed after lifting, if the High pressure jet is directed directly on to the paddle wheel it will spin so fast that the tiny magnet can be thrown out. Without it of course the transducer gives no signal. Took me ages to work out what was wrong with the log.
Its said to be a favourite game with the yard boys when cleaning off - see how high a speed they can get the log to register with the pressure washer......
Cure is of course a replacement paddle wheel. An older transducer if the plastic gets damaged the water can get in and rust the magnet jamming it.
<P ID="edit"><FONT SIZE=-1>Edited by oldharry on 19/08/2002 08:22 (server time).</FONT></P>
tgalea
Member
Re: Sensitive adjustments...
Thanks for the info. Yes the log still works i just get no reading. Looks like the magnet is my problem.
Looks like i'm up for a new unit!
Any further help will be appreciated.
Cheers
Tyrone.
Thanks for the info. Yes the log still works i just get no reading. Looks like the magnet is my problem.
Looks like i'm up for a new unit!
Any further help will be appreciated.
Cheers
Tyrone.
bedouin
Well-known member
Re: Easy....
My installation is also very sensitive to fouling on the hull around the transducer. Any build up of slime/weed there and the log first under-reads then stops reading all together, however clean the transducer is.
This is usually a sign that it is time for a scrub, but I can improve things a lot by poking a toothbrush down the transducer hole (with the transducer out of course) and giving a quick scrub.
I think this is probably a poorly designed unit for it to be so sensitive - I didn't have that problem with the old B&G one
My installation is also very sensitive to fouling on the hull around the transducer. Any build up of slime/weed there and the log first under-reads then stops reading all together, however clean the transducer is.
This is usually a sign that it is time for a scrub, but I can improve things a lot by poking a toothbrush down the transducer hole (with the transducer out of course) and giving a quick scrub.
I think this is probably a poorly designed unit for it to be so sensitive - I didn't have that problem with the old B&G one
G
Guest
Guest
Plan ahead!...
I was as concerned as you about pulling this plug thing out of the bottom of my boat and replacing it with the blank one I found neatly chained to the inner housing. So I gave myself the best chance by firstly getting comfortable in the depths of the bilge, then I arranged for plenty of light on the subject from a leadlight and finally applied a dollop of Vaseline to the bit to be inserted and put it ready to hand.
With both hands I carefully eased out the offending transducer paddle wheel holder, the incoming water squirted about 2 ft in the air straight on to the 240v lead light, blowing the bulb to bits and knocking out the pontoon fuse which plunged me into darkness. The rush of water caused me to fall over and drop the the bung which was swept away.
Remembering the story about the little Dutch boy and the dyke, I held my hand over the hole as best I could and shouted for my wife, who was reading her book on the flybridge. Either at the end of her chapter or when she realised the boat was settling in the water somewhat she rescued me and apart from yet another cuffing round the ear for being such a prat everything turned out OK in the end.
But don't worry worse things happen at sea!
Bernie
I was as concerned as you about pulling this plug thing out of the bottom of my boat and replacing it with the blank one I found neatly chained to the inner housing. So I gave myself the best chance by firstly getting comfortable in the depths of the bilge, then I arranged for plenty of light on the subject from a leadlight and finally applied a dollop of Vaseline to the bit to be inserted and put it ready to hand.
With both hands I carefully eased out the offending transducer paddle wheel holder, the incoming water squirted about 2 ft in the air straight on to the 240v lead light, blowing the bulb to bits and knocking out the pontoon fuse which plunged me into darkness. The rush of water caused me to fall over and drop the the bung which was swept away.
Remembering the story about the little Dutch boy and the dyke, I held my hand over the hole as best I could and shouted for my wife, who was reading her book on the flybridge. Either at the end of her chapter or when she realised the boat was settling in the water somewhat she rescued me and apart from yet another cuffing round the ear for being such a prat everything turned out OK in the end.
But don't worry worse things happen at sea!
Bernie
philip_stevens
Active member
Re: Sensitive adjustments...
If you are getting a log reading, then the magnet is still in place. It is the magnet that gives both speed and log readings. Some paddle-wheels have two magnets (Navman) and some have only the one.
It looks at though the display unit is giving the fault of no speed indication, if you are still getting a log reading.
regards,
Philip
If you are getting a log reading, then the magnet is still in place. It is the magnet that gives both speed and log readings. Some paddle-wheels have two magnets (Navman) and some have only the one.
It looks at though the display unit is giving the fault of no speed indication, if you are still getting a log reading.
regards,
Philip
Bobingabout
New member
I too had this problem a couple of weeks ago, and when we safely at anchor, removed the impellor, removed the weed, replaced it and all OK. Only about 1/2 gallon of water in the bilges.
Then my crew said (A techno!!), "Why didn't you do the job while the boat was moving through the water? You would get a Venturi effect, and so less water would get into the boat".
Hmm....I would have thought more water would be forced in.
Has anyone any thoughts, or even tried this?
Then my crew said (A techno!!), "Why didn't you do the job while the boat was moving through the water? You would get a Venturi effect, and so less water would get into the boat".
Hmm....I would have thought more water would be forced in.
Has anyone any thoughts, or even tried this?
G
Guest
Guest
Re: Easy....
I always remove the log before I leave the boat and replace it with the bung. I only get a coouple of pints of water in which is quickly dealt with a sponge.
I always remove the log before I leave the boat and replace it with the bung. I only get a coouple of pints of water in which is quickly dealt with a sponge.
AuntyPodes
New member
Re: Easy....Vaseline?
I'm not sure vaseline is good for rubber - doesn't it perish ? Silicone's the thing for keeping rubber soft.
I'm not sure vaseline is good for rubber - doesn't it perish ? Silicone's the thing for keeping rubber soft.
G
Guest
Guest
My transducer doesn't have the flap, but I still don't get very much water in, probably about a pint. Don't rush putting teh bung in or you might drop it into the bilge or cross thread it. Nowadays I remove the transducer every time I leave the boat. The hole for my transducer is about 2 feet below the waterline. Sometimes I put the transducer in under way (when I forget to put it back in when returning to the boat). I didn't notice any significant increase or decrease in the rate of flow compared to stationary.
p.s. I've also dismantled and serviced a seacock a fair way below the waterline (cooling water intake on Contessa 32). That caused quite an impressive fountain for a second or two before I put a temporary wooden bung in, but that was no bother either and actually only let about a couple of pints into the boat. It was enough to get me wet, though.
p.s. I've also dismantled and serviced a seacock a fair way below the waterline (cooling water intake on Contessa 32). That caused quite an impressive fountain for a second or two before I put a temporary wooden bung in, but that was no bother either and actually only let about a couple of pints into the boat. It was enough to get me wet, though.
vyv_cox
Well-known member
I don't recall many times when I have removed the log impeller at anchor. I'm almost always moving, reacting to some observed problem with the reading. Plenty of water comes in. Velocity would need to be a good bit higher for a venturi to work.
kdf
New member
Re: Easy....
From experience - don't try this while the boat is moving. The pressure is MUCH higher - more like a jet of water coming in!!!
From experience - don't try this while the boat is moving. The pressure is MUCH higher - more like a jet of water coming in!!!
vyv_cox
Well-known member
Que?
How can pressure be much higher? The head is exactly the same, whether the boat is moving or not. There is a general tendency for pressure to reduce where flow increases, hence the question re venturi effect. So in theory, although almost certainly not observable in practice, the inflow of water would be slightly less when the boat is moving than when stationary. I have never noticed any difference whether moving or not.
How can pressure be much higher? The head is exactly the same, whether the boat is moving or not. There is a general tendency for pressure to reduce where flow increases, hence the question re venturi effect. So in theory, although almost certainly not observable in practice, the inflow of water would be slightly less when the boat is moving than when stationary. I have never noticed any difference whether moving or not.