In hull Transducers

Designs for inboard or outboard power

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kens
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Re: In hull Transducers

Postby kens » Tue Nov 21, 2017 7:15 pm

May I ask, please.??
Why cut a hole in your hull, just to plug it with a fiberglass window of some sort, just to install a 'in-hull' transducer.
The main part I cannot comprehend is that most people don't want to cut a hole in their boat, I understand that.
but the rub is that you must cut-a-hole-in-your-boat in order to install that fiberglass window in the first place ???
Forgive me, I don't get it.

If you cut-a-hole-in-your-boat and install a proper "through-hull" you have effectively plugged that aforementioned hole-in-your-boat with an engineered, tested, documented part that is specifically designed to plug the-hole-in-your-boat and also be a darn fine transducer (without any coupling fluids) at the same time. It is engineered per various deadrise angles, and tested, and proven.

I'm sorry, I must ask, WHY??
please help me understand.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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raymacke
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Re: In hull Transducers

Postby raymacke » Tue Nov 21, 2017 9:09 pm

I was too cheap to buy one of the "real" through the hull units.


KENS - I already answered that! :lol:
(already had the the transom mount)
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Re: In hull Transducers

Postby Adrock1 » Mon Nov 27, 2017 11:16 am

kens wrote:May I ask, please.??
Why cut a hole in your hull, just to plug it with a fiberglass window of some sort, just to install a 'in-hull' transducer.
The main part I cannot comprehend is that most people don't want to cut a hole in their boat, I understand that.
but the rub is that you must cut-a-hole-in-your-boat in order to install that fiberglass window in the first place ???
Forgive me, I don't get it.

If you cut-a-hole-in-your-boat and install a proper "through-hull" you have effectively plugged that aforementioned hole-in-your-boat with an engineered, tested, documented part that is specifically designed to plug the-hole-in-your-boat and also be a darn fine transducer (without any coupling fluids) at the same time. It is engineered per various deadrise angles, and tested, and proven.

I'm sorry, I must ask, WHY??
please help me understand.


In my case, I don't want my boat to have any penetrations below the water line. My fiberglass "window" was put in before the hull was faired and fiberglassed. The net result is that it's totally integrated with the hull. I don't intend to cut through that window in order to install a thru hull transducer, although I easily could without the worry of cutting through wood and introducing the chance for water to get to that wood.

I'll glue a transducer down to that window, possibly even the standard transom mounted transducer that most units come with. I know folks who have done this with great success. The end result is that my hull will continue to have no penetrations below the waterline.

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kens
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Re: In hull Transducers

Postby kens » Mon Nov 27, 2017 12:13 pm

To me, a hole is a hole, it doesn't matter if one executes a repair with a fiberglass window or not. It's a hole.

I got a hole in my boat too, and I plugged it with a chunk of bronze and a bronze flanged structural nut 60x2mm threaded. That's about a 2 1/4" fine thread, I trust it is integral with the boat.

If you glue down a transducer to the window, then how do you ever service it? What if a new whizz-bang upgrade comes out? Can you replace the output cable? Can you change out for any upgrades?
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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JoeM
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Re: In hull Transducers

Postby JoeM » Mon Nov 27, 2017 12:45 pm

I personally don't see the reason to go through the trouble to create a window so you can use an in-hull transducer unless you are planning on running in very skinny water or routinely beach and are afraid of a thru-hull sheering off and opening a big gaping hole in your boat.

To each their own though. I can sort of understand if you already had the transducer and didn't want to get a new one.

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jamundsen
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Re: In hull Transducers

Postby jamundsen » Tue Nov 28, 2017 7:12 pm

I have 15 holes in the bottom of the boat. 2 are drains.
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steveh41
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Re: In hull Transducers

Postby steveh41 » Tue Nov 28, 2017 7:21 pm

Me too John... 13 plus 2 shaft logs, no drains.
The longest journey begins with a single step… then repeat as necessary!

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Re: In hull Transducers

Postby Adrock1 » Wed Nov 29, 2017 7:38 am

JoeM wrote:I personally don't see the reason to go through the trouble to create a window so you can use an in-hull transducer unless you are planning on running in very skinny water or routinely beach and are afraid of a thru-hull sheering off and opening a big gaping hole in your boat.

To each their own though. I can sort of understand if you already had the transducer and didn't want to get a new one.



I don't want holes in my boat below the waterline. So my options are an in hull transducer or one mounted to the transom. But I don't want one mounted to the transom because it's ugly and requires I drive screws into the transom below the waterline.

So if I'm going to go with an in hull transducer (not a through hull) I have to have a window of fiberglass because the transducers don't work when they shoot through plywood.

I can use the transducer that comes with my depth finder most likely. If not there are several option for in hull transducers. Either way though, I had to create a place in the hull where the transducer would only have to shoot through fiberglass as opposed to plywood.

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JoeM
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Re: In hull Transducers

Postby JoeM » Wed Nov 29, 2017 9:25 am

I definitely understand the need for a "window" in a plywood hull if you choose to use an in-hull transducer.

After reading through your Overnighter build, I understand why you want no holes below the waterline. You intend to beach regularly. I also would be wary of having a transducer or other appendage either sticking out or get plugged up with rocks and sand.

And BTW, your build looks great! I'm going to keep up with your build!

I personally would still drill an oversized hole, epoxy fill, redrill correct size hole, and install a drain plug. But that's my personal opinion, to each their own.

This next bit i'm not sure of as i'm rather inexperienced in working with fiberglass and resins. Though I have been on both wooden and fiberglass boats and have been able to compare the feel of the hulls, by hand at least. I would also be a little wary of having a super hard area of the hull that won't flex surrounded by wood that will when beaching. I would think the constant flexing would impart stresses on the joint area, weakening it, possibly leading to a failure similar to the shearing off of a thru-hull transducer. I do see that you have both fiberglass and xynel(?) which while giving lots of abrasion resistance I don't know that it imparts enough stiffness to where flexing won't happen at all. And while epoxy is used in laying the fiberglass and xynel, the coats aren't that thick. When you create the "window", isn't it much thicker than the amount layed on the wood and fiberglass? Doesn't that make it much stiffer and more resistant to flexing when compared to the rest of the hull?

I'm in no way saying I'm right and everyone should do what i'm doing. There are so many trade-offs and compromises we each must make in order to reach our individual end goals. Learning from each other's experiences and why they did the things they did can only help us all.

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kens
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Re: In hull Transducers

Postby kens » Wed Nov 29, 2017 9:58 am

Guys,,,,,C'mon STOP it !!!
on a thru-hull xducr there is nothing 'sticking out' to break off. Look it up, please.
They are available with about a 1/8" height, and even then, they are faired/blended out about 1/2" around. there is nothing there to catch nor hang up on anything.
Yes, there are some that protrude, but not all. You guys are talking about stuff that does not exist.
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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kens
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Re: In hull Transducers

Postby kens » Wed Nov 29, 2017 10:06 am

is this what one looks like that 'sticks out' from the hull??
http://www.airmar.com/images/products/b785m.jpg


here is one that is flush:

http://www.airmar.com/images/products/b60.jpg
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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Jimbob
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Re: In hull Transducers

Postby Jimbob » Wed Nov 29, 2017 10:08 am

When I had my Wellcraft runabout I added a Hummin Bird depth guage / fish finder. It came with a tranducer similar to the picture below. I mounted it on the outside of the transom. The only hole going through the transom was for the cable. The instructions said you could epoxy it to the inside of the bottom of the boat but, didn't recommend it. It was mounted so the bottom edge of the tranducer was even with the bottom of the boat, so it would be in contact with the water. Since it was under the waterline, you didn't see it except when the boat was on the trailer, like the speedo pickup. (before gps).
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JoeM
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Re: In hull Transducers

Postby JoeM » Wed Nov 29, 2017 12:07 pm

kens wrote:Guys,,,,,C'mon STOP it !!!
on a thru-hull xducr there is nothing 'sticking out' to break off. Look it up, please.
They are available with about a 1/8" height, and even then, they are faired/blended out about 1/2" around. there is nothing there to catch nor hang up on anything.
Yes, there are some that protrude, but not all. You guys are talking about stuff that does not exist.


kens wrote:is this what one looks like that 'sticks out' from the hull??
http://www.airmar.com/images/products/b785m.jpg


here is one that is flush:

http://www.airmar.com/images/products/b60.jpg


I hate to partially disagree Kens but I do. And yes, I've looked it up and yes I have some practical experience in this. And yes, this stuff exists.

Yes, there are flush mounted thru hull transducers. Correct, they won't hang up on anything. They can be damaged by beaching though. Try beaching and having the transducer sit on that one rock at just the right angle. Think that can't happen? Ask my cousin. Is it going to happen everytime? No. But something I would want to keep in mind if I were beaching and had a thru-hull.

Thru-hull transducers with fairing blocks, like the first one you posted, do stick out (some installations more than others) and can be damaged. It's not so much that it CATCHES on something, it's that rather than have the impact or weight spread over the hull, it's instead concentrated on the ~2" hole with slim transducer. Sort of like the bed of nails, spread out over an area nails can support weight but concentrated in one area and damage ensues. I actually have some experience in this as the 24' Skipjack had a thru-hull transducer with a fairing block. It stuck out over an 1" in places. We had to replace the trailer bunks but had to cut out a portion of one of the bunks because of the transducer. Otherwise the boat would sit on the transducer not the hull. Now is it guaranteed that the hull would have been damaged? No, but i'd rather not damage the transducer either since replacing it would be costly. Thru-hulls with fairing blocks can damage the hull if an impact from a rocks or something hits the transducer. As I mentioned before though, if something is able to tear out or puncture the thru-hull transducer location the hull would likely have been damaged without the transducer there anyways.

Again though, i'm not saying that one type of thru-hull is better than the other. Because again, we all have different goals. I'm going to be building a coastal boat that if I see skinny water I better be hauling it out on a trailer or i'm in real trouble. So having a thru-hull isn't an issue for me.

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kens
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Re: In hull Transducers

Postby kens » Wed Nov 29, 2017 3:03 pm

" Yes, there are flush mounted thru hull transducers. Correct, they won't hang up on anything. They can be damaged by beaching though. Try beaching and having the transducer sit on that one rock at just the right angle. Think that can't happen? Ask my cousin. Is it going to happen everytime? No. But something I would want to keep in mind if I were beaching and had a thru-hull."

The same thing applies to a fiberglass window, if you park your boat on a rock, I would worry about punching the window out.
What kind of damage did he get? Did he bust one of the flush mounted ones, or, the fairing one?
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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JoeM
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Re: In hull Transducers

Postby JoeM » Thu Nov 30, 2017 1:05 am

Was a flush thru-hull that was busted. He cracked the assembly (his words), no damage to the hull but he had to replace the unit as it would no longer function. While damage in this way is maybe not likely to happen, it is possible.

I agree, the same thing does apply to fiberglass windows. Though in my cousin's case, he may have been fine(minor repair if that) beaching on that one rock angled at just the right position since there was no major hull damage, just transducer damage.

As a side note, He hadn't had an accident like this and he replaced with a like transducer and hasn't had a repeat performance in a few years. I have heard of damage to fairing block through hulls but that is my only flush mount thru-hull that I've heard of being damaged that way. But then again, I haven't looked for that information specifically so maybe it's more prevalent than I think.

I personally would use a transom mount in his case, but again, that is my personal preference.


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