B275 or B265 thru-hull transducer on Express 330

[BRO-CAL]

I’m looking to install a B275LHW thru-hull transducer on an Express 330 but it is a beast of a transducer and space in the aft bilge with generator is very tight. Is anyone running this or the B265 thru-hull transducer on an Express 330? If so, please let me know where you mounted it. Not interested in a transom mount but I know that is an option. Thanks!

 

[Sardinia306Canyon]

Installer of ex owner installed my same size B265LH center keel on the fairing block and the position is exactly there where the lifting straps go and she got hauled with the rear strap over the transducer what is definitively not cool.
I am waiting to get a quote to pull the B265LH and have it glassed flush center keel to solve the drag issue and that the sling lift boat on it.

I believe the 330 Express has also the transducer pockets, but it seems to me that the original airmar fairing block is too big to fit in the pocket, but can maybe shortened to fit there. That would be the best place and should be accessible as designed by GW.

I can't remember how the 330 Express bilge area is, my B265LH is in the empty bilge space after rear fuel tank, approx 4ft forward of transom.

Chris

 

[HMBJack]

I don't know if mine is the same size but here's some info.

I installed an Airmar B175H to starboard of the ~6" high rib that's down in there. This is one of two structural ribs that you see in the aft bilge area.

There is a pretty decent sized flat area there and mine is a chirp with 20 degree tilt. I used a properly sized hole saw and sealed it with 3M's 4200 polyeurathane sealant. Works great and no leaks.

 

[Sardinia306Canyon]

I don't know if mine is the same size but here's some info.

No it's a total different transducer, in shape and size.
The Airmar 164/165/175 series is a wide stem but very flat head transducer not needing an fairing block while the 265/275/285 are traditional shaped transducer needing in general a high speed fairing block, however, both are thru-hull transducers.
I did not measured the transducer installation pad/area but by eye measure the B275 fairing block will not fit there.

 

[Sardinia306Canyon]

This is my B265LH and it's fairing block, the B275LHW has the same size

 

[BRO-CAL]

Here's a picture of the aft bilge. There are raw water pickups for the generator and air conditioner and ideally this giant transducer needs to go forward of those. As you can see - virtually no room to do anything in here as the fuel tanks are forward of the raw water pickups. Looking for any creative ideas out there - someone with an Express 330 must have gone down this path before...

 

[Sardinia306Canyon]

Urgh, yes this looks crammed ....

I think i remember the transducer installation pads also on the 30 Express, but not 100% sure.
It would be important to know if your hull has this two transducer installing pad's or not, if your boat is on the hard you can see them from the below the boat..
If GW designed this pad there, then there must be a way to access it but as it looks removing some stuff is probably involved.
If you don't get a answer here then you should check in your 330 Express user manual if there is a chapter about transducer installation, if not contact GW directly.

One option may be If space between the Generator and hull inside is enough then removing the generator and installing the transducer under the generator and installing the generator again.
But then you will have the transducer sticking out of the hull as mine does and shown in the photos i posted.

Chris

 

[BRO-CAL]

Urgh, yes this looks crammed ....

I think i remember the transducer installation pads also on the 30 Express, but not 100% sure.
It would be important to know if your hull has this two transducer installing pad's or not, if your boat is on the hard you can see them from the below the boat..
If GW designed this pad there, then there must be a way to access it but as it looks removing some stuff is probably involved.
If you don't get a answer here then you should check in your 330 Express user manual if there is a chapter about transducer installation, if not contact GW directly.

One option may be If space between the Generator and hull inside is enough then removing the generator and installing the transducer under the generator and installing the generator again.
But then you will have the transducer sticking out of the hull as mine does and shown in the photos i posted.

Chris

No pockets or pads on this hull. Will be reaching out to Grady customer service next.

 

[Sardinia306Canyon]

Well, in this case things become more complicated.

If you did not bought the B265LH already then you change transducer type to two B175HW or MW and a B175L for example. Installation will be similar complicated due the space limitations, but they are very flat and don't have a fairing block what would stick out as mine does.
Also sign where the slings go, unfortunately installer mounted mine exactly there where the stern sling goes and thats not good.
If you want the B275LHW (what is one of the best transducers) then i suggest to have it glassed in flush to hull center keel (probably under the generator), that would reduce drag from the even more gigantic fairing block.

The cheapest solution would be fabricating a sturdy L shaped bracket out of U shaped SS and bolt it on the transom center keel between the engines and either not use the fairing block or make a minimal size one to avoid turbulence.
I made this back in about 2005 for my BW 23 outrage and it worked well.

Let us know what GW customer service says, it may be interesting for some here.

Chris

 

[BRO-CAL]

Update - installing B175HW and B175L thru-hull transducers both in the aft berth area. The B275LHW just didn't make sense on this boat unless I wanted to pay to have a pocket created for it in the keel $$$$ Also have a GT51M-TM transducer that came with the boat mounted in between the outboards. Why have 1 transducer when you can have 3?

 

[Sardinia306Canyon]

That is a wise decision!
The B265/275 series is the best transducer for extreme use but the big size makes it awkward and/or pricy to install.
Double 175 setup will solve you a lot of minor problems and they should give you the best result for it's size.
Once you get used to side-scan you will love it for finding structure down to about 200ft and the GT51M is a rather old but still the best deeper water side-scan transducer on the market and a very useful tool.
I will get one again but still deciding if a TH, the double TH or simply the between the engines transom mounted model.
It may be necessary to trim the outboards a bit up (a vertical or a bit more up) to avoid that side-scan will be partially blocked by the lower units, but i will discover that in a few months.

Chris

 

[MLC]

I installed a B275LHW center keel where my forward bilge pump is located in my 330. I installed epoxy blocks on each side to accommodate the new locations for the bilge pump and switch. Both pump and switch had plenty of extra wire and room for the move. I also installed a TM 3 in 1 a couple inches off center to starboard. They both work great hooked up, even in rough water. I used the same location some years back for a B275 in a 265 express I owned. It worked great also. I do believe that getting the transducer face down in the water stream improves performance vs. a flush mount. I would install it center keel to prevent it from pulling your boat to the side it's located while hooked up. In both installs, I didn't experience any negative effect on speed or fuel economy.

 

[BRO-CAL]

I installed a B275LHW center keel where my forward bilge pump is located in my 330. I installed epoxy blocks on each side to accommodate the new locations for the bilge pump and switch. Both pump and switch had plenty of extra wire and room for the move. I also installed a TM 3 in 1 a couple inches off center to starboard. They both work great hooked up, even in rough water. I used the same location some years back for a B275 in a 265 express I owned. It worked great also. I do believe that getting the transducer face down in the water stream improves performance vs. a flush mount. I would install it center keel to prevent it from pulling your boat to the side it's located while hooked up. In both installs, I didn't experience any negative effect on speed or fuel economy.

Send some pictures of your B275LHW please. I’d like to see the forward bilge area and under the boat. Thanks!

 

[MLC]

I'll take one of the inside installation and send later, unless my dock is still covered in snow.

 

[MLC]

Here you go. If you go this route, let me know and I'll share what I learned.

 

[Sardinia306Canyon]

Nice install!
The brownish thing is a handmaid counter plate?
What is the flat part on the hull where the counter plate is resting on? Original GW transducer installation pad or you made it?

Thruhull transducers who stick out quite a bit can be install midships, had to install one on on my scuba diving rib as only accessible space was under the console mid ship and it worked great.
However i would not install it flush there, for flush mount installation the transducer should be most back as possible where water at center keel has less bubbles.

Chris

 

[MLC]

The boat shaped brown thing is the top of the transducer fairing block. The platform it is on is per Grady for the bilge pump and switch. At this location the fairing block can be cut flush and shaped with a 5" orbital sander to match the bottom contour. The flush cut was perfect for the top piece of the block to seal in the hull here. I used thicken epoxy to make new platforms for the bilge pump and switch, leaving a channel for bilge water to flow to the stern.

 

[Sardinia306Canyon]

Nice job and thanks for the explanation!
Chris

 

[SkunkBoat]

Can't tell from your pix but when you mount centerline, you can shorten the height of the fairing quite a bit because there is no hull angle to match.. It only has to be as thick as the bronze transducer housing.

That would also be a great place for a GT51M-TH. Don't even need a fairing. You can glass a flat spot and flush mount it.

Question for Bro-Cal... what is in the boat now? I'm surprised there is not already thruhull like an old B744

 

[Sardinia306Canyon]

That would also be a great place for a GT51M-TH. Don't even need a fairing. You can glass a flat spot and flush mount it.

Yes, i am still thinking about how and where to install the GT51M.
As i have already the huge fairing block center keel, installing the GT51M in front or behind will probably reduce high speed reading of the transducer behind due turbulence. Or i install the GT51M-H center keel under the console what would be about mid ship and that should work reasonable well and for sure at less than planing speed.
Most expensive solution would be to install a pair GT51M-THP on the GW transducer pad's my hull has.
Or just install the GT51M-TM on the transom what would be less invasive solution with the risk of reduced high-speed reading, what would not be a problem for me as i use side-scan only at slow speed.

The GT51M is so narrow that i would expect that on the round hull of my 306 or the 330 no glass work to make a pad is needed, just a bit more 5200 to fill the tiny difference.

Chris