Transducer through hull install

[IBeGrady'd]

I'll be replacing my old lowrance GPS/Sonar soon and I'm thinking that replacing the old transducer might be prudent (or necessary). Anything thru hull makes me nervous and I've zero experience with anything below the waterline.

Is this a do it yourself project or something best left to a pro?

Thanks

 

[DennisG01]

First... if the current transducer is working and COMPATIBLE with the new one, I'd leave it be for now. You're not really saving any labor time by doing it now as compared to later. But, I'll answer the question based on replacement...

It is a DIY, but it all depends on the "Y". If you're uncomfortable with it, have a pro do it. It's probably a 2-hour-ish job, max. Could be money well spent for piece of mind. Would I do it myself? Sure. Would some other people that answer do it themselves? Sure. But, honestly, what I (or others) do, has no impact on you. Do what feels right for you. Download the instructions, read them a couple times, and see what you think.

 

[seasick]

I agree that if the current model is working, you should leave it for now.
Secondly, if you are uncomfortable putting a hole in your hull, you will sleep better by not planning on doing so
If you do go ahead, there are two critical issues to address: Getting the correct model x-ducer and installing it in the correct spot. The later issue is really important because if in a bad spot there is no fix other than to move it and patch the first hole. The best way to find out the optimal location is to find folks with the same hull and see where they installed the transducer and if it works as needed. Often, the best spot on the hull is not easy to get to inside the bilge.
Good luck

 

[IBeGrady'd]

First... if the current transducer is working and COMPATIBLE with the new one, I'd leave it be for now.

I agree that if the current model is working, you should leave it for now.

I was thinking exactly that but I guess unit of choice may make that decision for me.

It is a DIY, but it all depends on the "Y". If you're uncomfortable with it, have a pro do it. It's probably a 2-hour-ish job, max. Could be money well spent for piece of mind...Download the instructions, read them a couple times, and see what you think.

Will do...thanks.

...If you do go ahead, there are two critical issues to address: Getting the correct model x-ducer and installing it in the correct spot.

Something to be careful about...thanks.

 

[Harpoon]

transducer removal....

They don't come out easy. The last one I removed needed to be cut off with a sawz-all. Then I pushed it upward with a 3 ton jack, the hull lifted off the trailer for a moment and it popped through.

Next, clean the opening I used a rasp to remove all the old 5200 and get back to clean glass. Then I sealed the layers with some resin. Once that was all hardened I applied copious amounts of 5200 to the sides, top and bottom of the opening and replaced the ducer. Put blue tape anywhere you don't want sealant, latex gloves and paper towels and paint thinner are handy too. Allow the 5200 to cure properly, 3-5 days depending on temperature prior to going back in the water.

 

[DennisG01]

It's best not to use 5200 for this. It's way overkill for the application. In this instance, we're just looking for sealing water out, with a slight adhesive advantage. 5200 is too strong. In some instances, 5200 will separate the gelcoat from fiberglass during removal. Something like 4200 or even BoatLife LifeCalk would be the more appropriate product.

Harpoon - This advice isn't meant for you as you've already done it. It's just for anyone else reading this so they avoid the mess you had to go through to remove that transducer. 5200 "get's around" on the interweb and it often seems like it's a magical, cure-all. But the truth is, there are actually very few occasions where it's the right product for the job. For those times, it's great. But for most other jobs, there are better products.

 

[Harpoon]

I work for a manufacturer of polyurethane adhesives. 5200 is a very cleverly formulated and robust product.
It has been modified/improved by the supplier over the years. That sort of overkill is exactly what I'm looking for when sealing a 2" hole at the bottom of my boat or holes passing through my transom. Other applications, not so much. Incidentally, the job I was discussing with the jack and sawzall was installed on a Parker with boatlife polysulfide. It's pretty good stuff too. I haven't compared the chemistry of 4200 vs 5200. I think its just faster setting?

 

[DennisG01]

4200 is not quite as strong. 4200 is very similar to the BoatLife LifeCalk in terms of strength. Both of them being just a step down from 5200.

The problem with 5200 (I use the word "problem" lightly since it is an excellent product for it's intended purpose) is that it creates a stronger bond, in most cases, between it and the gelcoat than the gelcoat to fiberglass bond. Imagine if someone had actually used 5200 for your transducer - there most likely would have been some decent physical damage.

If one was simply gluing something to the bottom of the hull, then I would absolutely use 5200. But with a thru-hull ducer, the primary means of attachment is mechanical. In that case, a sealant is all that is needed. That being said, I agree that it's a good idea to use something with some adhesive qualities, just not a "super glue" :mrgreen:

I've worked in the marine industry for close to 30 years and I've seen the issues that 5200 can create when use in the wrong application. Think about stern drives... that's an even bigger hole through the transom. Manufacturer's don't use 5200 there for the same reasons. It's not needed for that application and using it will only cause headaches when/if the transom plate assembly has to be removed due to damage or excessive corrosion.

 

[max366]

3M provides good data on their products. Shear strength gives you an idea of its adhesion. 5200 on fiberglass- 362 psi. 4200 on fiberglass - 165 psi. So 5200 has about 2X better adhesion strength. However, the gelcoat value for 5200 is 519 psi (not given for 4200) so it adheres even better to gelcoat.