Through Hull Transducer Help

[rost495]

Ordered a B60 20 degree through hull transducer to put in this weekend.

Have a question-- I cannot see the inside bottom of my hull in many places. I have two "steps" in the bilge area either side of hte drain tube. A float switch screwed to one side, and a pump to the other. Evident that this step area must be made to screw things to without penetrating the hull.

My question-- I'm thinking I can cut a hole in that area, to access the hull and then even drill the hole from the bottom up, put all back in and glass back over.

Wrong or right?

Also viewed from the stern, I have a center drain tube, and then a water intake to the right of that tube. Single outboard in center with jackplate offset.

I"m thinking transducer should be to the left of the engine is the best place for it.??????

Hull is Hydra Sport 21 foot CC, circa 84 IIRC.

Thanks for any input!

Jeff

 

[dingbat]

Re: Through Hull Transducer Help

I installed the same transducer in my Grady back in Feb. this year. The installation was a piece of cake and I have nothing but good things to say about it.

Are you sure that hull is cored? I didn’t think that it is but I’m certainly no expert. On mine they just glassed in a couple of pads to mount the switches and the rest of the bilge is solid. The B60 will accommodate roughly 3 to 3 1/2" in thickness so you have some room to play with.

As for the location, I put mine roughly 16-18” in from the back of the boat and roughly 8” off center, starboard. I have 2 scoop intakes (wash down and live well) on either side and a transom mounted speed sensor to deal with but since everything including the prop is behind the transducer you don’t have any “dirty” water from them to contend with.

 

[rost495]

Re: Through Hull Transducer Help

Excellent-- Hydrasport cannot tell me if its cored or not. I'll just have to do a bit of drilling or cutting. If I find it solid its reassuring to know it can probably work as is. That would be way better than the way I"d anticipated!!

Thanks much!!

Jeff

 

[dingbat]

Re: Through Hull Transducer Help

Good luck. Let us know how things work out.

 

[Texasmark]

Re: Through Hull Transducer Help

Before you start cutting and pasting, you might run a performance test.

Get a milk jug and cut both ends out of it. RTV it to the anticipated location and fill with water. Or if you can, just fill your bilge with water to a depth that will cover the transducer where you think you want to mount it.

Take the boat out to a spot where you can get good returns, preferably at the depth of interest.

Put the transducer over the side and record your presentation.

Move the transducer inside the boat to where you think you want to mount it. Might tilt it or move it around for best effect.

What you see is pretty much what you'll get. So if you like what you see, epoxy that sucker there and forget the saw and patch.

Mark

 

[dingbat]

Re: Through Hull Transducer Help

Before you start cutting and pasting, you might run a performance test.

Get a milk jug and cut both ends out of it. RTV it to the anticipated location and fill with water. Or if you can, just fill your bilge with water to a depth that will cover the transducer where you think you want to mount it.

Take the boat out to a spot where you can get good returns, preferably at the depth of interest.

Put the transducer over the side and record your presentation.

Move the transducer inside the boat to where you think you want to mount it. Might tilt it or move it around for best effect.

What you see is pretty much what you'll get. So if you like what you see, epoxy that sucker there and forget the saw and patch.

Mark

The B60 is a thru hull transducer, not a shot thru. Installation of this unit requires that you punch a 2 1/2" diameter hole through the bottom of your boat. The transducer installs from outside of the hull and is held in placed with a large nut using the supplied gasket and 3M 4200 as the seal.

It’s basically a 3" diameter x 6" tall piece of brass in which the transducer is installed at an angle to accomandate a particular dead rise. They make a 0-12 degree and a 12-24 degree unit for use in boats with the same dead rise.

Great transducer but certainly not for everyone.

http://www.airmartechnology.com/airmar2005/ex20/RMProducts/ElectCat.asp?ProdID=36&Man=All&PageNo=67

 

[rost495]

Re: Through Hull Transducer Help

Bit of help again, got a hole cut in the bilge area, to get to the hull bottom. Then found lots of globs of gelled glass.... anyway after long time with chisels etc.... got the area flat as I could. Put 3M 101 sealant around the bottom of the hole, coated inside the hull, a very thin layer inside on the bottom, and a good layer on the B60 itself. Pushed it through, arrow towards center or keel line. Rubber washer and brass nut but as I tightened the nut, the washer keeps slipping out. I know the bottom is not perfectly flat but layup is that way.... It should be sealed totally from the outside.

This is high dollar sealant, for below water line, and takes 2-3 weeks to cure.

My question is everytime I tighten the nut more the washer slips out. I"m thinking maybe leaev it for a few weeks, and then snug it up more? I wiggle the unit as much as I can and there is NO movement on the bottom at all.

Advice there??

Thanks, Jeff

 

[dingbat]

Re: Through Hull Transducer Help

Tighten it up the best you can and let it go. Tighetening it up later will only stress the joint.

Some don't even bother with that darn gasket. The seal is between the bottom flange and the hull so the gasket is more of a feel good than anything.

I have to ask why did you use 3M 101? Most everyone I know installs them with 3M 4200 fast cure and it's done in 24 hours.

 

[rost495]

Re: Through Hull Transducer Help

101 cause I'm dumb.... well really, it was order through the mail and I needed to seal drain plugs. 3M has so many..... I told em it was for drain tubes and thats what I got....

It'll be weeks or months or years till the boat is in the water anyway so no big deal. This way I can go back tommorrow and snug up the nut, and not worry about it, washer or not.

Thanks, Jeff

 

[gregtobin]

Re: Through Hull Transducer Help

Would the through hull transducer work if you mount it on the outside of the transom? This might be easier.

 

[dingbat]

Re: Through Hull Transducer Help

Would the through hull transducer work if you mount it on the outside of the transom? This might be easier.

Transom mounts are notorious for bad performance. On top of that most mid to high performance transducers like the B60 are quite massive. This particular unit weighs roughly 5-6 lbs. Can you imagine hanging a brick off your transom on the end of a bracket?

 

[rost495]

Re: Through Hull Transducer Help

Would be tough to patch a 2 and 3/8 inch hole in the hull anyway.

Its on tehre for better or worse now.

Thanks for all the help.

Jeff