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carioca1232001
12-10-2003, 08:17 PM
Just recieved my NAVMAN 4100 fishfinder with PLASTIC through hull transducer.

The Transducer installation manual says:

".....They are not recommended for use in all types of wooden hulls as expansion of the wood may cause the fitting to fail mechanically. It is possible to install plastic through hull transducers in some plywood or solid wooden hulls. The hull must be well laminated and sealed with epoxy resin to prevent expansion of the wood through absorption of moisture. The responsibilty to use a plstic transducer in a timber hull is that of the owner. If in doubt you should consult a marine surveyor or marine engineer. "

Considering that:

A. The sales literature made no mention of the limitations of PLASTIC through hull transducers;

B. The hull on my boat is not laminated nor sealed with epoxy, and neither is it going to be for this application,

Question 1 : Could the problem be solved by sawing a hole in the planking, say, 1/8 " (one-eigth of an inch) larger in diameter than that recommended by the manufacturer, and seating the transducer in a generous helping of polyurethane sealant ?

I am presently replacing the first two planks by the keel, on port and starboard, with IPÊ (pronounced "e-pay" !) wood, a hard, heavy, oily wood species, virtually immune to rot, and which is being exported from Brazil to the US for luxury garden decking and seaside boardwalks.

The through hull PLASTIC transducer will be installed over the second IPÊ plank on port.

Question 2 : By virtue of IPÊ´s basic properties and usage for outdoors and traditional boatbuilding (schooners etc.) in Brazil, may it be inferred that this wood should also be dimensionally stable when immersed in water, by not absorbing the latter in great quantities ?

JimJ
12-11-2003, 08:13 AM
Have a look at these threads

http://media5.hypernet.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic&f=1&t=008309&p=

http://media5.hypernet.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic&f=1&t=006129&p=

Stu Fyfe
12-11-2003, 08:42 AM
I've done exactly as you suggested on my strip plank hull without any problems. The transducers have been in place for 12 years. My hull is sealed in epoxy with polyethylene fabric. Inspection has shown no cracks or stress.

cbob
12-11-2003, 12:43 PM
Carioca, Just installed a Standard Horizon digital readout this spring, transducer mounted clamped with backing nut in a section of the worm shoe. The transduces that were available from Standard were not the exact shape of the previous transducer, which could no longer be used as different frequency, i.e. 150 hz verses 100 hz, so found there were 100 kz transducers on the market, other than Horizon, that were exact duplicates. Learned this from a local Marine Electronics shop/dealer, Sausilito, California, who was able to locate and supply same overnight. Outstanding service, anyway I'm not familiar with your unit, but my opinion for what it's worth, is to locate and install a suitable bronze transducer, correct hz, and stay away from plastic if possible. Check with your supplier, there may be a suitable bronze transducer available for your new finder/sounder. BTW put in about 800 sq. ft of ipe' ashore in a an outdoor deck structure, expect it will outlast me, and it sinks too. good luck cbob

cbob
12-11-2003, 12:45 PM
Carioca, Just installed a Standard Horizon digital readout this spring, transducer mounted clamped with backing nut in a section of the worm shoe. The transduces that were available from Standard were not the exact shape of the previous transducer, which could no longer be used as different frequency, i.e. 150 hz verses 100 hz, so found there were 100 kz transducers on the market, other than Horizon, that were exact duplicates. Learned this from a local Marine Electronics shop/dealer, Sausilito, California, who was able to locate and supply same overnight. Outstanding service, anyway I'm not familiar with your unit, but my opinion for what it's worth, is to locate and install a suitable bronze transducer, correct hz, and stay away from plastic if possible. Check with your supplier, there may be a suitable bronze transducer available for your new finder/sounder. BTW put in about 800 sq. ft of ipe' ashore in a an outdoor deck structure, expect it will outlast me, and it sinks too. good luck cbob

J. A.Tones
12-11-2003, 01:06 PM
I have had two plastic transducers installed on my boat for the past 15 years with no problems. The hull is carvel planked western red cedar and the fairing block is the same cedar. I installed them as you suggested with a bit of clearance around the shank and then set them in Sikaflex (a one part underwater sealler), then tightened the backing nuts up just snug enough to force lots of excess out. Once the Sikaflex was set I tightened up the backing nuts about 1 turn more and left it at that. Just removed them a few weeks ago during the re-fit and there was no sign of seepage around the transducers and the planks were in fine shape.
I would not attempt to install plastic transducers if the planking was really dry without leaving lots of slack in the backing nuts for a week or two untill the planking has had a chance to swell after relaunch.
John

Bruce Hooke
12-11-2003, 02:23 PM
J.A.Tones raises an important point that should, I think, be emphasized. The diameter of the hole may actually not change that much as the plank shrinks and swells. If anything it seems to me that the hole might get slightly bigger as the plank swells, because as the plank swells it gets wider, but I'd geuss that in reality, on a plank constrained by adjacent planks, the difference would probably be quite small. HOWEVER, the plank, backing block and so on will get thicker as they take up water, which could be an issue. So, just focusing on the diameter of the hole is not sufficient.

Gerald
12-11-2003, 02:24 PM
Like J.A. I also have two thru hull transducers, also mounted in red cedar. One of them had been in the hull for 36 years. Both were set in Wanda massa sintetica or equivalent. Ipe is a little different animal than cedar. I am not sure how much Ipe would swell but I would guess darn little. Worst case scenario ....... it swells and breaks the jam nut. Do any of us here really think the transducer will fall out? After removing the nut I had one heck of a time removing the transducers from the hull, then again in my case the putty did have a good chance to set up. I would go along with what has been said here and like was said before leave the entire setup loose and tighten as required. So what if it leaks a little ...... ya got a sump pump. smile.gif
Gerald

Dan McCosh
12-11-2003, 02:36 PM
I ran into this problem as well. The issue referred to is the idea that a plank clould swell enough in thicknesss to crack the threaded portion of the transducer. I doubt this is a major problem by itself, although a stack of backing blocks, fairing blocks, etc. could be much different than a single plank. A larger issue I ran into is that the plastic transducers are thick and short, which means a larger hole in the plank. Also, in my boat the transducer requires a lot of blocking to make it verticlal--something probably not a problem on a powerboat or flatter-bottom sailboat. The bronze tranducers are thinner pipe, and longer. They are available, but in my case cost more than the whole depth sounder. An alternative is to mount the whole thing in a block screwed to the planking, and just run the wire itself through the planks.

carioca1232001
12-12-2003, 06:04 PM
Thanks EVERYBODY for the many solutions offered. Is anyone aware of unsolved problems on this Forum ? !

Cbob, just for the record, I had 2 (two) Standard Horizon 220 S fishfinders fail on me PREMATURELY, one after the other. Hopefully, the NAVMAN will do better.
You´ve deciphered BTDT before, but what does BTW stand for ? Yes, IPÊ (e-pay)will go to the bottom of the drink if let loose, but will also last a lifetime !

Bruce Hooke, I read your post on the engineering properties of wood etc. in connection with a different issue. Very impressive ! Which species up north is similar to IPÊ ? Yes, will need to leave some slack on the nut (on the transducer stem) to address board swell thickness-wise.

High C
12-12-2003, 06:09 PM
Hey, speaking of transducers, does anyone know if they are brand specific, or can they be used with differents brands of sounders. I have a Standard sounder I'd like to replace with another brand, but don't want the bother of changing the transducer. Neither company's website offers the answer to this question.
:confused:

Thanks :cool:

High C
12-12-2003, 06:26 PM
Thanks, Donn. That tells me what I need to know.

Bill Dickinson
12-14-2003, 08:58 PM
I don't think anyone else mentioned that Navman can sell you a bronze transducer. They did for me and it will go in this spring.

carioca1232001
12-15-2003, 04:45 PM
Bill,
I did notice that they also market a bronze transducer.
The plastic one was part and parcel of the 4100 Fishfinder package - all yours for US$129 which is hard to beat !
Don´t think there will be problems with the operation of the plastic transducer as the necessary countermeasures will be taken during it´s installation.