TomCat transducer: Finding the Sweet-spot

M

Mike...

New member
Hello to all.

I am going with a thru-hull transducer (not a shoot-thru), and I seem to remember there is a some place in one (or both?) bilges that is solid glass.

Would one of you TomCat owners please point me in the right direction?
---
mike
 
Hi Mike,
I found it incredibly difficult to find but once I found it - it seemed very obvious somehow.

You have to look very closely - get your head down there as much as possible with a light. You will notice the slight indentation that appears to be about 12" X 12" as Charlie said above - starboard side forward of the bilge pump.

Good luck.

--Matt
 
Are you using a flush style transducer, or will it be using a fairing block?

The fairing block style will require certain placement that may fall outside the non cored area, and could disrupt water flow to the engine, possibly causing ventilation and over heating issues.
b744v_fairing.jpg


The flush style units don't have a paddle wheel, but are good performers. Units with tilted elements offer great performance, and are available in 1Kw models. They require bigger holes, and we have installed a couple in deep v hull trailered boats to avoid having a transducer and fairing block hanging down to get caught on the triler bunks or rollers.
b117.jpg



Check out Airmar's website- http://www.airmartechnology.com/
 
I don't know fellas, my head is pretty big. :)

Of course it doesn't help that the TomCats are designed to repel all attempts by their owners to accessing the bilge.

Charlie, you'll loan me your long-armed monkey, right? I'll let you hold on to one of my kids as collateral. (...and may God help you there...)

So did you fellas install your transducer there? If so, how did you seal it. It just seems so wrong to drill holes through a perfectly good hull!

Matt, thanks for the Airmar ink. We are planning a flush mount with temp (like your second example -- thanks for the pics). I am hopeful that GPS speed will be accurate enough.
--
mike
 
Mike...":3bhbzorx said:
...

So did you fellas install your transducer there? If so, how did you seal it. It just seems so wrong to drill holes through a perfectly good hull!

...
Click to expand...

Hi Mike,
Your choice of terminology at the start threw us...you said you were going with the thru hull not the shoot thru. The thru hull means drilling, the shoot thru means no drilling. Your post above leads me to believe you actually want the shoot thru type to avoid drilling.

It's one of those funny terms that make no sense..."In-hull" is the actual term for shoot thru but makes no sense. Ha ha!

Although contrary to the instructions on my Airmar In-hull aka shoot thru transducer, I used 3M 42 or 5200 to seal the fluid tank to the hull. The instructions called for silicone but I find that is not strong enough.

I scuffed my hull with sandpaper, cleaned it up good with acetone, then installed the transducer fluid tank with 42/5200. Once cured, I added my non-toxic antifreeze, set my housing offset angle to 14 degrees, and installed the transducer unit. 3 seasons strong with zero problems.
 
GPS speed over the ground will be more accurate, than a paddle wheel speed thru the water.

Usually one makes a backing block--I prefer solid teak--for the transducer inside of the hull. 4200 for the transducer, and 5200 for the back up block.

Now if you want to know how to do it with the boat in the water--you will have to send me a PM.
 
matt_unique":3gepe5jk said:
Hi Mike,
Your choice of terminology at the start threw us...you said you were going with the thru hull not the shoot thru. The thru hull means drilling, the shoot thru means no drilling.
Click to expand...
Nope - I do mean thru hull. We are indeed drilling.

I just don't have to like it, that's all. :)

It will probably be the AirMar B164, but I have to figure out the tilt.

Any thoughts on this one?
---
mike
 
If you promise to keep the kids, I'll GIVE you the monkey! I have had kids and learned my lessons 2X. Once I put in my big hatches, I'll be able to let the monkey go. Hatches will be on the way shortly from my buddy Marc at Wefings.

BTW, I found out they pronounce it "weeeeefings", not "wefings" as I thought it to be...Learn something every day.
 
Captains Cat":1lb2l9fg said:
If you promise to keep the kids, I'll GIVE you the monkey! I have had kids and learned my lessons 2X.
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Darn! No one ever takes me up on that deal. :)

Captains Cat":1lb2l9fg said:
Once I put in my big hatches, I'll be able to let the monkey go. Hatches will be on the way shortly from my buddy Marc at Wefings.
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Great; I hope it makes things a little easier for you.

Still, I think we need more access down there. If I have time before the boat has to go into winter storage, I am going to go with the Beckson plates fore and aft in each of those Damn Leaky Fishboxes. And maybe also install the the neat vents Brian installed in his (at the bottom of his post).
---
mike
 
Mike, those aren't "vents" they are drains. They will drain the water to a box like your shower sump where you'll have to install another pump. More to deal with. Why not cut a small hole in the BOTTOM of the boxes and let them drain into the bilge where you already have a pump? KISS principle.

I still don't want your kids.... Why not get one of those new life insurance policies where, they give you the money now and when you pass into the next world, THEY have to pay it back! You'd be surprised how their attitude towards you and your well-being changes!!

Charlie
 
thataway":2uct78nl said:
GPS speed over the ground will be more accurate, than a paddle wheel speed thru the water.
<stuff clipped>
Click to expand...

True but it really depends on what your purpose is for the paddle wheel. If you fish, what matters while trolling is speed relative to the water (which is what you get from the paddle wheel). Speed over the ground is great for navigational purposes but not so much for trolling. So in my mind the real question is "What's the application for which you want to know speed - navigation or fishing?"
 
Captains Cat":3jipna8l said:
Mike, those aren't "vents" they are drains. They will drain the water to a box like your shower sump where you'll have to install another pump. More to deal with. Why not cut a small hole in the BOTTOM of the boxes and let them drain into the bilge where you already have a pump? KISS principle.
Click to expand...
This was the vent that Brian mentioned (well, I think he called it a vent). I was planning on mounting them in the floor of the boxes so that water can drain into the bilge. So, I think you are in sync there. :)

But the problem is that this defeats the point of a self-bailing cockpit a bit. However, if we end up in rougher water, I suppose I can put the little green plug in.

Captains Cat":3jipna8l said:
I still don't want your kids.... Why not get one of those new life insurance policies where, they give you the money now and when you pass into the next world, THEY have to pay it back!
Click to expand...
Heh - great idea. :)
---
mike
 
rogerbum":3pwwkick said:
So in my mind the real question is "What's the application for which you want to know speed - navigation or fishing?"
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Hi Roger.

Good question. Navigation. Our idea of fishing is perusing the menu at our favorite restaurant. :)
---
mike
 
thataway":wz81cprj said:
Usually one makes a backing block--I prefer solid teak--for the transducer inside of the hull. 4200 for the transducer, and 5200 for the back up block.
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Hi Dr. Bob.

I must be missing something. So are you saying 5200 the block to the hull and drill through both to mount the transducer? Then tighten down the nut onto the block?
---
mike
 
Excellent point Roger--but it also depends on where you are trolling. For example, much of our fishing is in open ocean, both West Coast and Gulf Coast--as well as on ocean crossings, where currents are miminal. If you are in the PNW, and salmon trolling--they the paddle wheel is key!

Mike,
No, I predrill the hole in the backing block. Then the hole in the hull. Put the 5200 around the outer edges of the backing block--the 4200 on the transducer, stem and around the hole (including on the mating face to the glass by the hole) as I slide the transducer in place--then tighten the nut--the nut will hold the backing block and transducer inplace while the 4200 and 5200 go off. If you put in a larger transducer later, you would then have to reem out the backing block.
 
Thanks Dr. Bob. That is helpful.

I have to say, though, that I am not crazy about drilling a 3" hole through the hull, I alternatively talk myself into it, then talk myself out of it again.

At this moment, I'm in the mindset to do it. But tomorrow, I might talk myself out of it again. :shock:

Who knows.
---
mike
 
Mike...":vrfv3d4v said:
Thanks Dr. Bob. That is helpful.

I have to say, though, that I am not crazy about drilling a 3" hole through the hull, I alternatively talk myself into it, then talk myself out of it again.

At this moment, I'm in the mindset to do it. But tomorrow, I might talk myself out of it again. :shock:

Who knows.
---
mike
Click to expand...

Try it with the "shoot through the hull" first Mike. If you don't like it, you can always drill the hole. OTOH, if you do it the other way, you gotta find something to do with that hole. :cry

Charlie
 
Ha ha - reminds me of a few short years ago when I was kneeling on the roof of the then brand new Napoleon with a brand new drill bit. X marks the spot!

I know the transducers that contact the water are more accurate but I sure like the fact that I did not add a hole below the water line! Then again, my idea of fishing is like yours (except for lobster diving).
 
If you won't be fishing, then the small loss of resolution won't negatively affect sounder performance for you.

Go with the 1kW in hull transducer and you won't need to drill holes, or worry about transducer against the trailer bunks.

Even for fishing, the 1kW unit in hull works very well.
 
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