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Mounting bronze thru-hull..impact concerns...

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Mounting bronze thru-hull..impact concerns...

Old 12-06-2003, 04:26 AM
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Default Mounting bronze thru-hull..impact concerns...

I'm gonna move up to a bronze thru-hull for my 582L. It's going on my mako261 so I would like to mount it right on the centerline without a fairing block. I am a very careful boater and do not use the boat in shallow water. I guess my real concern would be hitting a submerged object and ripping the transducer out, but I see that as a very remote possibility. I think the object would require a sharp edge and strike exactly right to actually do any damage. A rounded object would probably deflect off. Am I fooling myself with these assumptions?
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Old 12-06-2003, 05:36 AM
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Default Mounting bronze thru-hull..impact concerns...

The answer to your question depends in part on which transducer you plan to use. I am assuming it is the depth/temp only, not the larger "triducer" with the paddlewheel. A soft grounding is not really much of an issue. A bigger risk would be a careless yard attendant when you haul the boat, who might put a sling at that location and put the whole weight of the boat on your transducer. You have to remember that the transducer itself is just a urethane plastic insert in the bronze housing. They are not meant to take any signficiant loading.

With the smaller depth/temp transducers, you can use the small fairing blocks that are the size of the bronze housing. Why not play it safe and offset it from the keel just enough so that the transducer is not the lowest point? Alternatively, if you know a good glass guy and want to put some money into the project, you could get a transducer mounting recess fabricated. If you can find a 32 Regulator, go look in the bilge and you will see an oval box right on the keel line. This allows a transducer to be mounted flush with the keel and then faired totally smooth.
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Old 12-06-2003, 07:37 AM
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Default Mounting bronze thru-hull..impact concerns...

I've had numerous soft grounds with thru hulls and never so much as harmed the paddlewheel on a thru hull mounted right on the centerline.

I also hit something (probly a submerged log) once and broke off one of the two stems on the particular transducer I was using at that time (double stem Depth, Speed, and Temperature unit). Even with one of the two stems broken loose and the transducer spun around 90 degrees against the hull there was no water leakage into the boat (though we removed the boat from the water very quickly as you might immagine). The same thing would be likely true in the even of a severe strike that broke a single stem transducer (as virtually all of the transducers from AirMar are these days I believe) free of the hull would not ususally result in water in the boat.

The reason I say that is that unless you lost the transducer to a sea monster who bit down on it and pulled it out of the boat, by yanking the 7th of his 9 vile heads, its likely that it was sheared off by the strike against something more mundane. If its sheared off then the transducer stem is still in the hull and still passing through the inner part of the fairing block. All of this is held in place by the liberal amounts of your favorite goop and it 'ain't goin' nowhwere'. Seriously, most bangs against the hull bottom even the big ones, won't hurt the thru hull. Of course that isn't always the case and carrying a set of tapered wood plugs is always important (drill a hole through the one that corresponds with the stem size and use a lenth of brass chain to secure it near the transducer mounting and never remove it).

So that's it. The long and the short is that there isn't much you can do about hitting stuff sometimes, particularly in murky water filled with debris. Don't worry about it too much.

Thom
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Old 12-06-2003, 08:42 AM
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Default Mounting bronze thru-hull..impact concerns...

Thom, I knew if I waited long enough I'd get the answer I was hoping for. I figure if I hit something hard enough I'd hear it, feel it and see my engines kick up.That would definitely inspire me to check all my thru-hulls fittings, including the transducer, and deploy wooden dowels as needed. Now to find the best deal on a thru-hull!!!
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Old 12-06-2003, 10:56 AM
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Default Mounting bronze thru-hull..impact concerns...

Oh, you'll know when you bang one all right.

I've said t his before but maybe I should mention it again. Every spring I put our boat in a local lake for a day or two. I'm just makeing sure everything is working OK and trying to get a little heads up on my boat handeling lack of skill (I'm terrible at boat handeling) for the year.

The local lake we use is really a dammed river that feeds down out of the mountains of east-central West Virginia. This is some remote area, and heavily forrested. There is a lot of logging activity these days and of course every winter brings lots of dead fall. In the late winter the ground is usually saturated and as the thaw comes so does a lot of water. The result is that lots and lots of debris finds its way into that lake by early spring. Some of this stuff is made up of complete trees, big ones, saw logs find their way, limbs the size of three men's legs aren't all that uncommon either. A lot of this stuff floats but a lot more of it hovers just below the surface. You can't see 2 feet into the water either, by the way. We hit so much stuff during those couple of days that it would scare the hell out of any old Off Shore fisherman. If I had to take a guess I'd say that we get 10~20 strikes a day and two or three of them will be the kind of Big Thumps that really get your attention. I don't know how Sloopy can stand it (he lives on that lake).


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Old 12-06-2003, 05:23 PM
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Default Mounting bronze thru-hull..impact concerns...

quote:I don't know how Sloopy can stand it (he lives on that lake).


Thom


How do I stand it? Well fist it helps A LOT if you know where things collect on the lake and where the big floater is. (the big floater is a huge tree at least 50 feet long and 3 feet wide, 2 people have completely destroyed there outdrives on the floater) Most debris collect on the sides around the bends and turns in the lake. I have learned from copying taildraggers as they taxi is to do LONG S shapes when going up and down the lake. T
Thom I can show you some good spots... and not so good spots if you like.....

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Old 12-09-2003, 07:34 PM
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Default Mounting bronze thru-hull..impact concerns...

Mounting a little off center is the best way, just be sure to cut the faring block at the correct angle to match the deadrise of the hull so that the transducer points down. My dealer installed transducer was almost 10 degrees off. In several 100 feet of water I was looking way off to the side. Use a floor jack to level the boat on the trailer, then use a torpedo level to level the transducer. Also if you buy a high speed faring from Airmar you can taper the leading edge from the unit down to the hull allowing the unit to ramp over any foreign object.

tex4771 23'Parkerpilothouse, Cypress, Texas
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Old 12-10-2003, 09:42 AM
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Default Mounting bronze thru-hull..impact concerns...

quote:Originally posted by tex4771:
Mounting a little off center is the best way, just be sure to cut the faring block at the correct angle to match the deadrise of the hull so that the transducer points down. My dealer installed transducer was almost 10 degrees off. In several 100 feet of water I was looking way off to the side. Use a floor jack to level the boat on the trailer, then use a torpedo level to level the transducer. Also if you buy a high speed faring from Airmar you can taper the leading edge from the unit down to the hull allowing the unit to ramp over any foreign object.

tex4771 23'Parkerpilothouse, Cypress, Texas

Why bother? It seems to me that a few, even 10, degrees off would be negligable compared to the listing caused by waves and people. No ones boat sits perfectly level in the water. What am I missing here?

2003 Parker 23SE CC - Yamaha F225
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