Using RTV sealant on a suction cup to adhere better to my fiberglass transom

[Pain'n'da'boat]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

I set it up in the bilge but used RTV sealant thinking as long as the air bubbles were eliminated, I would be ok...plus I assumed the epoxy would be 100% permanent and in the event it didn't work properly, I didn't want to be out $100...didn't think about the absorption into soft sealant...oh well, going out tonight so I don't have time to re-do with epoxy but I will at least get an idea if it will function...

For shoot-thru hull I am assuming the temp sensor will be inaccurate?

 

[smokeonthewater]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

correct.... you may get some reading with the rtv but the epoxy will work much better... BTW I have removed several that had been epoxied in.... wasn't easy but none broke yet

 

[Pain'n'da'boat]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

I didn't realize it until last night, but the old depthfinder that Im pulling off, since it's broken, was epoxied in the bilge...I got it off without hurting anything and was able to have a really clean surface to work with...i will def re-do with epoxy this weekend.

OH YEA, any kind of epoxy? any kind specific I can pick up at any local home-improvement store?...this is my first time to do this.

I did get the transducer to sit down in the rtv low enough to touch the fiber glass when I was trying to keep air bubbles out, the RTV is more like a cradle around it instead of a bonding agent. I hope it works ok enough for tonight, that would be awesome!

I appreciate all the help smokeonthewater, and everyone else that helped me out in here.

 

[zagger]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

I wanted to to say to use denture cream on the suction cups since I first Read this thread but did not know if it would be received with humor. Anyway, I found 60 minute epoxy to be the best because it stayed in liquid form for longer allowing any bubbles to escape from under the transducer. Just create a small dike (you can use play dough) around the area where the transducer will be placed. then locate it in place, I like to use a small wood dowel through the mounting hole and rest it on the dike edges. Mix your epoxy in a small cup and tap it on a table to force air baubles to top. Slowly pour the epoxy into blocked area, I also found that if you pour from a single corner the epoxy will migrate around the transducer without trapping air. Pour only enough so it comes up half way up the unit, that will hold it well and make removal much easer if you need to do it at some point. Let it set and go fishing, you will love how it performs at any speed.

 

[Pain'n'da'boat]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

I wanted to to say to use denture cream on the suction cups since I first Read this thread but did not know if it would be received with humor. Anyway, I found 60 minute epoxy to be the best because it stayed in liquid form for longer allowing any bubbles to escape from under the transducer. Just create a small dike (you can use play dough) around the area where the transducer will be placed. then locate it in place, I like to use a small wood dowel through the mounting hole and rest it on the dike edges. Mix your epoxy in a small cup and tap it on a table to force air baubles to top. Slowly pour the epoxy into blocked area, I also found that if you pour from a single corner the epoxy will migrate around the transducer without trapping air. Pour only enough so it comes up half way up the unit, that will hold it well and make removal much easer if you need to do it at some point. Let it set and go fishing, you will love how it performs at any speed.

thats a good idea and my kids have tons of playdoh. I've got a skimmer type ducer and it's rounded on the bottom, so the idea of making a cradle sounds like the easiest way to ensure a good grab. Thanks zagger!

 

[smokeonthewater]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

biggest thing is when you mix it, do it in slow motion..... best way to get rid of bubbles is to never make em in the first place... I personally have always used 15 minute epoxy except for when I was out and used 5 minute..... 4 minutes to mix and 1 to pour.... better be PREPARED tho with the fast stuff and if you goof and make bubbles just toss it and start over

 

[John_S]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

At 40mph, if the transducer does come off, it will either snap the cable or be a projectile coming back in the boat. Suction cups are for portable mounts on relatively slow craft. It amazes me how much effort people will go through to not drill a couple holes. They include screws with a transom mount and not epoxy. Dried on 5200 or any epoxy is going to look worse than any screw holes, and be hard to scrape off without damaging gel coat.

 

[smokeonthewater]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

he has decided to epoxy it INSIDE the hull..... no projectile worries

 

[John_S]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

he has decided to epoxy it INSIDE the hull..... no projectile worries

OK, "embarressed", confession: didn't read all the way through the thread.

 

[Pain'n'da'boat]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

it works well using RTV sealant in the bilge when I am stopped but as soon as I get underway it starts going nuts, showing approx 1,500 fish directly under the boat and the depth shoots to 96' when I know its about 20-30' deep

epoxy will cure this right?

or will I have to tell my uncle that his old bass boat is getting holes drilled in the transom?
(it's still my uncles boat that he hasn't used in over 10 years...he has let me "borrow" for the last 3 years after it sat for 7-8 years untouched....he is what I am avoiding the holes in the transom, I personally would have already drilled holes and been done with it)

maybe one day I will be rich enough I can convince my wife that buying a bass boat is a much wiser purchase than some big ski boat...

 

[Pain'n'da'boat]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

When applying the ducer to the epoxy, am I supposed to let the part facing rearwards touch the epoxy, or does it need to be clear and clean?

or do I just make a playdoh box and fill with epoxy until it fills up to the center mark on the transducer? I am not knowledgeable on the science behind nor the mechanics of how transducers work...

i drew a confusing picture to help:

 

[smokeonthewater]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

you are simply gluing the bottom down to transmit sound.... the red line is PLENTY

The purpose of the "dam" is to allow enough epoxy to make a level surface on the slanted surface you are attaching to

 

[Pain'n'da'boat]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

you are simply gluing the bottom down to transmit sound.... the red line is PLENTY

The purpose of the "dam" is to allow enough epoxy to make a level surface on the slanted surface you are attaching to

thanks again for the help....do I need to make sure I avoid getting anything on the 'face'?

 

[smokeonthewater]

Re: Using RTV sealant on a suction cup to adhere better to my fiberglass transom

nope you could submerge it under 2 feet of epoxy...... would be a beach to remove though