How to replace transducer without sinking

[double u]

as opposed to speculation of various posters I'll take the liberty to describe how we actually put a throughhull transducer into our 37' aluminium keelboat while at anchor in Fannie Bay, Darwin, in a place where there was no hole:
3 people, 2 in the bilge, one in the water
1 plumbers friend
1 stainless saladbowl, flat rim, diameter ~10", bead of sikaflex sealant on the rim
1: drill 3mm hole from inside, when drillbit becomes visible under water put plumbers friend over it from outside, drillbit withdrawn, waterpressure pushes rubber bell strongly against hull. waterentry so far 3 thimblefuls.
2: cover hole from inside with thumb, after knocking from inside pf replaced by saladbowl, knock from outside, thumb removed from hole, waterpressure presses saladbowl strongly against hull (bottom of bowl visibly dished)
3: centered on the 3mm hole 2" hole cut with an electric holesaw (from inside of course), waterentry into boat additional 5 thimblefuls; flat piece of ply with towel pressed against hole from inside, knocking, saladbowl removed from outside (against surprisingly strong waterpressure), saladbowl handed up into boat
4: transducer w sikabead on sealing surfaces put into saladbowl & cable coiled nicely into bowl, sika-bead on bowlrim, cover with clingfoil, second sikabead on bowlrim, bowl handed overboard
5: bowl positioned over 2" hole, knocking, sealing plate inside the hull removed, area dried with papertowels, clingfoil on bowl broken, cable carefully fished from bowl & pulled through hole, transducer pulled up by cable & secured with it's mounting nut from inside, knock
6: bowl pried lose, sika on hull cleaned with spatula
surfaced relieved & proceeded to connect transducer up
altogether abt 50ml of water entered
comments: boat yawing at anchor & slight chop didn't help a lot
only on an aluminium boat would I ever do it exactly that way!
on fibreglass: the water would absolutely have to be kept away from the fibreglass edge & the edge sealed with epoxi! could be done but would be more work, entail a hairdryer to make sure the exposed edge is absolutely dry.
same on a steel or wood hull; on the steel hull of course the cutting of the 2" hole itself would be more troublesome.
As our procedure had worked so well we did it a second time as we discovered that the transducer was faulty (from new...). secondtime around we had a little bit more water enter (1/2 pint) as the faulty transducer had to be pushed out & recovered (warranty)
btw I guess a plasticbuckt would not stand up to the waterpressure of 50cm (20") depth that the transducer had to be mounted in

[sainted]

Originally Posted by TrentePieds

Quote: " The problem is, a lot of those thru hulls were glued in with 5200, which is a damned good adhesive."

Agreed. And the OP can't know if the thru-hull has been screwed, blued and five-two-ed. Doing an exchange of thru-hulls afloat is dodgy unless that is known.

I have a much easier but still annoying problem: The PO spent a shameful amount of money on a new rig, including four new Anderson winches. They are gooped down with 5200. The stripper bars are all wrongly oriented, one so badly that the winch is effectively no longer a self-tailer. On Andersons you cannot re-orient the stripper bar in relation to the winch body. You have to shift the winch body in relation to the gorilla's work position.

This job calls for a small hydraulic jack, some wedges and some fairly blue language :-)!

TrentePieds

Not to hijack the original thread, but use heat. 5200 will let go if you get it to about 300 degrees. Strip the winch and heat the base with a torch.

[belizesailor]

Originally Posted by sainted

Not to hijack the original thread, but use heat. 5200 will let go if you get it to about 300 degrees. Strip the winch and heat the base with a torch.

It also has poor chemical resistance.

[TrentePieds]

Sainted and Belize:

Thank you both! New skills need to be learned here :-).

I'm wary of the heat option, and given that the goop is mainly in the mounting holes surrounding the bolts, I think a solvent might take several sailing seasons to get to the root of the matter.

Upward pull on the winch via a bottle-jack, a lever and a fulcrum in combination with wedges driven under the base of the winch, peu a peu, will be my first approach. The goop is still fairly soft after about three years.

A torch judiciously applied to the mounting studs from below may make a contribution as the tension comes on the puller, and clean-up would obviously have to be chemical.

I think that once the winch is off, I am going to make a gasket to seat it on when I replace it in its new orientation. The faying surfaces would by coated with "monkey snot" - HD rubber cement - prior to popping the winch back in place. My present opinion is that that would avoid this silly problem, stemming solely from a "professional" riggers lack of forethought, next time I'll have to pull the winches.

TrentePieds

[belizesailor]

Originally Posted by TrentePieds

...
I think that once the winch is off, I am going to make a gasket to seat it on when I replace it in its new orientation. The faying surfaces would by coated with "monkey snot" - HD rubber cement - prior to popping the winch back in place. My present opinion is that that would avoid this silly problem, stemming solely from a "professional" riggers lack of forethought, next time I'll have to pull the winches.

TrentePieds

Yes, 5200 is WAY over used. You dont need an aggressive adhesive for thru bolted hardware, just a good sealant. Butyl is quite good for bedding hardware. I also like 3M 4000 UV. There is at least one long thread here about deck hardware bedding options...take a look at that too.

[Caleb C]

Wow CF Friends,
Lots of replies to this thread.
I'm reading your comments and will use suggestions this Friday afternoon for the project.

AT LEAST I DON'T HAVE THAT SINKING FEAR ANYMORE

Keep tuned for the results.

Meanwhile, if you want to watch the entertainment, come by Mission Bay. BYOB if you're not going to help

[Singleprop]

I'm not so afraid of changing the transducer after reading this thread - great info. Thx

[Mystic38]

This..

Also, the bright green light calling you to the deeps needs to be ignored...

oh, and if you wear glasses, they get full of water. just saying...

Originally Posted by UNCIVILIZED

You can swap it out while in the water without fear, well... mostly ;-) The first sight of the mini geyser is alarming, but in the time it takes to change it, you'll take on perhaps a gallon or three of water.
The adrenaline from it is actually a good reminder of why you always keep soft wooden plugs tied near each thru-hull. And to service the fittings, as well as your zincs regularly.

[Caleb C]

DIDN'T SINK THE BOAT and the bilge pump didn't even get a sip of water!


Thanks to all the CF comments on this topic!


The thought of having to replace the speed/temp transducer, while the boat was in the water, made me nervous. The CF members who have 'been there, done that,' and share their experience are gems.


So, for all the nervousness about the project, it turned out to be a yawn. I dove under the boat with the plunger and a knife while my boat partner removed and replaced the transducer from inside. The thru-hull sleeve didn't have a flapper to prevent water from coming in, but the new transducer came with an adapter to slip inside the existing thru-hull and it has a flapper. The new speed/temp transducer slips inside the adapter.


We preassembled the new transducer to the adapter sleeve using lube so the o'rings wouldn't dislodge and leak. I dove under the boat, scored the bottom paint from around the old transducer with a knife so it could be backed out. Then I knocked on the bottom of the boat the signal for my boat partner inside to unscrew the old transducer. I placed the toilet plunger over the thru-hull. When the transducer was removed, the plunger sealed itself around the hole. When the new transducer was installed, the plunger released itself. Minimal amount of water got inside which was easy to clean up with a few paper towels.


So, thanks again to all of you for the helpful comments sharing your methods for dealing with preventing water from sinking your boat when having to work on thru hulls and transducers.


Happy sailing!

[belizesailor]

Originally Posted by Caleb C

DIDN'T SINK THE BOAT and the bilge pump didn't even get a sip of water!


...

YAHOO!!!

[Rustic Charm]

Originally Posted by Caleb C

DIDN'T SINK THE BOAT and the bilge pump didn't even get a sip of water!

Thanks to all the CF comments on this topic!

The thought of having to replace the speed/temp transducer, while the boat was in the water, made me nervous. The CF members who have 'been there, done that,' and share their experience are gems.

So, for all the nervousness about the project, it turned out to be a yawn. I dove under the boat with the plunger and a knife while my boat partner removed and replaced the transducer from inside. The thru-hull sleeve didn't have a flapper to prevent water from coming in, but the new transducer came with an adapter to slip inside the existing thru-hull and it has a flapper. The new speed/temp transducer slips inside the adapter.

We preassembled the new transducer to the adapter sleeve using lube so the o'rings wouldn't dislodge and leak. I dove under the boat, scored the bottom paint from around the old transducer with a knife so it could be backed out. Then I knocked on the bottom of the boat the signal for my boat partner inside to unscrew the old transducer. I placed the toilet plunger over the thru-hull. When the transducer was removed, the plunger sealed itself around the hole. When the new transducer was installed, the plunger released itself. Minimal amount of water got inside which was easy to clean up with a few paper towels.

So, thanks again to all of you for the helpful comments sharing your methods for dealing with preventing water from sinking your boat when having to work on thru hulls and transducers.

Happy sailing!

Well done. you really didn't need to go diving though with the toilet plunger but whatever works for you is a win.