Marine Electronics Forum - Questions on ducer mounting setup

I think I'm done figuring out which FF I want and have settled on the GSD 24 which means I'll need to replace my transducer. Probably a x260 variant ducer but please read on. The boat is a Dakota 36' CC and it has an old B744 thru-hull ducer of unknown condition (wires were cut and no tags). The B744 was flush mounted in the hull but after reading the board and talking to Semperfi, it looks like I should use the fairing if I go with the thru-hull. Additionally, what appears to be an in-hull mounted just starboard of the thru-hull so I don't know if the in-hull option is another option. I 'think' the hull is solid fiberglass but I don't know the thickness. Take a look at the pics and let me know if staying with a thru-hull w/fairing is way to go or if something could be easier/better. I'm asking in the sense of total work involved, dollars spent and effectiveness of the FF since I know everything is a trade-off.

In other words, what would you do if you were going to fish out of Texas in the Gulf, usually under 400ft or so. Use a thru-hull? Install the fairing? Something else?

You can see the B744 just to the left of the drain hole while the in-hull is on the right side. And the boat is kept trailered, if it matters.

Being that you trailer your 36' boat the B260 pocket mounting may be the better option over the B260 with the fairing.

If you have a sound and solid fiberglass hull the M260 is an easy and less expensive install .

TheTm 260 is an option also...

At 400' depths with the GSD-24 ....and with a solid hull I would slightly favor the M260 due to less overall costs.

I just put in a M260 in supposedly a too thick hull for a GSD 24 upgrade on my regulator. I have only had it out to 120 ft this past weekend, but it worked fine. A noticeable improvement in target resolution from bottom and other targets. Install was very easy.
I trailer my boat and did not want the transom mount unless I just had to go that way. My first transducer was a B60 and I did no want to cut another hole in my hull.

Semperfi advised me. I think the sensitivity of the M260 coupled with a kw makes Airmar's precautions about hull thickness a nonissue. My hull is between 1.5 and 2 inches thick. I fish to similar depths as you noted.

I will post some screen shots from this weekend if the weather cooperates.

Nuts

The simple answer is: An in-hull transducer won't be simple.

After some more inspection, the bilge is actually a tub that rests on the hull so it is not a single solid piece of fiberglass. I thought the in-hull that is in there was in a molded hull pocket but instead, a hole-saw was used to cut through the tub so the in-hull touched the hull. To use an in-hull, I'll have to do some sawing through that tub. Not impossible, but not simple either.

I popped out the old transducer using a piece of all-thread and some scrap aluminum from the shop. I am SO HAPPY it was sealed with only RTV! With this info, is the B260 the way to go instead of the M260? The B260 should just pop back in, right??? If I don't use a fairing for the B260, how much effect will this be? I'm guessing it will only affect the FF while moving, but at what speed will I start having issues?

I know, tons of questions but I really appreciate all the insight from the board.

Nuts-looking forward to those pics. Gil- as always, many thanks!

On option here.
You can add a pocket mounted B260 in place of your B744 hole....after all you are halfway there.
You will have excellent sonar capability.
50 times better than the B744.

A good many members have added a B260 in a pocket mount configuration...a very positive approach.

I downloaded the Airmar brochures for the B744, B260 and B265 and it looks like the B2xx form factor is significantly larger than the B744. About 3" longer, 1.5" wider, and a 1.5" thicker base. Won't get back to the boat until Sunday to see if that pocket can be enlarged enough to accept it.

Nothing's simple I guess.

I downloaded the Airmar brochures for the B744, B260 and B265 and it looks like the B2xx form factor is significantly larger than the B744. About 3" longer, 1.5" wider, and a 1.5" thicker base. Won't get back to the boat until Sunday to see if that pocket can be enlarged enough to accept it.

Nothing's simple I guess.

Hey..bigger is better:grin:

The B260 element is 8.5" long...the B744 element is 5.55" long

But, you will really want to start over and just use the existing hole as your location.
You will want to make a completely new pocket.

That sure makes the transom mounted a bit more attractive....or cut thru the tub and still mount a M260.

Hey Gil- Might want to double check that length. From the brochures, the 7" length is the B258 and the B260 is 8.5".

But what I have to figure out is the thickness of my hull. I gave up last night when it started getting dark because my best guess was it was almost 3" thick where the pocket was located! I can see where the pocket protruded just a bit (1/2") from the hull but I'm having a hard time believing the hull is really that thick.

Hey Gil- Might want to double check that length. From the brochures, the 7" length is the B258 and the B260 is 8.5".

But what I have to figure out is the thickness of my hull. I gave up last night when it started getting dark because my best guess was it was almost 3" thick where the pocket was located! I can see where the pocket protruded just a bit (1/2") from the hull but I'm having a hard time believing the hull is really that thick.

Duh...! :bashhh:

Right ..8.5"' for the B260..I have not had my coffee this morning...good catch.

After much hemming and hawwing this weekend, I'm now leaning towards the M260 in-hull mount as the B260 pocket mount will require significant fiberglass effort. The use of a fairing is possible for the B260 but I it would interfere with water flow back towards the center engine. The cleanest and easiest route would be to remove the old round in-hull mount and widen the cut out in the tub to accommodate a M260.

So here are some questions for in-hull mounting. From what I can measure, the hull is almost two inches thick at the mounting site but it also has a 22deg deadrise making the effective thickness around 2.5" of fiberglass. Anyone think this is too much? How much loss is expected? Does the deadrise cause any other issues?

From what I can measure, the hull is almost two inches thick at the mounting site but it also has a 22deg deadrise making the effective thickness around 2.5" of fiberglass. Anyone think this is too much? How much loss is expected? ?

That is too much hull thickness for an effective signal with the M260.
I double checked with Pete from GEMECO and he concurs ..too thick.:(

Well, so now it sounds like either a TM260 or back to a B260. The B260 requires a lot of fiberglass work whereas the TM doesn't. But then again, I've heard a lot of frustration regarding transom mounting 260's...

Well, so now it sounds like either a TM260 or back to a B260. The B260 requires a lot of fiberglass work whereas the TM doesn't. But then again, I've heard a lot of frustration regarding transom mounting 260's...

Another option.
You can get the TM260 elements in a flush mounted pair:

http://www.thehulltruth.com/fishing-miscellaneous-items/427355-tht-member-special-ss264-flush-mount-pairs.html