Thru-hull transducer mounting location on 330 Express

[everwhom]

Hoping to hear from some other 330 Express owners...

When I purchased my 330 from its previous owner, the boat had a sonar thru-hull transducer mounted exactly on the keel, right between the thru-fulls for the generator and air conditioner. I replaced the transducer with a new Garmin GT51M-TH (chirp/sidescan) which works great off plane but faster than 17knots, I get too much noise to see anything useful (still holds bottom though).

I'm realizing that the placement on the keel is a bit unusual, and my marina is suggesting I move it to one side. So basically 2 questions for any 330 express owners:

1. Where is your thru-hull transducer mounted and
2. Do you have a clear picture at cruise speed (i.e. can you still see fish clearly below?)

Many thanks!!

Joe

 

[Rustygaff]

How far forward is the GT51 mounted forward of the transom edge? I have the same dilemma. I just purchased a GT51-TH and plan to keel mount it but I have a couple of raw water strainers that may give it some turbulence. I am going to crawl under the boat later today and take some measurements to see exactly how far those strainers are mounted away from the centerline.

 

[everwhom]

Ah - hopefully we can solve this together...

Just heard from Grady - they're official recommendation is shoot-thru or transom mount, so not super helpful, but I'm hoping to hear more.

My keel mounted thru hull is located exactly between the air-conditioning and generator pickups so probably about 6 feet from the stern.

 

[Rustygaff]

I just went out and crawled under my boat with a tape measure. The leading edge of the 2 strainers are 40" forward of the transom edge and are offset from the centerline by 6". I should be able to mount the GT51 either between the strainers or just in front of them and still be close enough to the stern to be OK. I would like to mount it further back but am not sure if a 6" gap between the CL and the strainers is enough to avoid turbulence.

 

[SkunkBoat]

The GT51 has sidescan. Your best bet for mounting one is on the centerline or your hull will block the sidescan on one side.

Like your 33, my 265express has a thru hull between the water intakes. That one is an Airmar 50/200 connected to a GS22 sonar unit.
One major consideration is easy access to the interior side on the hull. You have easy access where the intakes are ...thru a big deck lid.
Anywhere else is probably under a fuel tank.

I bought a echo94sv sidevu with transom mount GT51.
Going to mount between motors. Probably won't work very good at high speed but the old thru hull does.

I was thinking about putting a thru hull GT51 centerline way fwd where the fwd bilge pump is.
Again, won't work at speed but will be perfect for trolling /anchoring.
Problem is Thru hull GT51s just cost way too much.

 

[2 Little Time]

My transducer is significantly to the starboard side, just beyond the starboard end of the generator. Function is good at cruising speeds. I will try to remember to take a photo next time I am on the boat.

 

[2 Little Time]

Further clarification, my transducer is the old Furuno; no side scan.

 

[everwhom]

Thanks for the replies.

Rustygaff: here's a picture of where my GT51 is mounted now as circled. My marina is suggesting we move it off to the port side. I realize I'll lose side scan to starboard if I do this, though if I really want it, I can get another GT51 for the starboard side like 2 Little Time. In truth, I've never used the side-scan. I spend most of my time fishing in pretty deep water where the structure is only the bottom contours. I'd much rather have a clear sonar picture at cruise than side scan any day.

2 Little Time: can you still see fish at cruise speeds?

 

[jip40]

My transducer is significantly to the starboard side, just beyond the starboard end of the generator. Function is good at cruising speeds. I will try to remember to take a photo next time I am on the boat.

Mine is mounted same as this

 

[Rustygaff]

Thanks for the replies.

Rustygaff: here's a picture of where my GT51 is mounted now as circled. My marina is suggesting we move it off to the port side. I realize I'll lose side scan to starboard if I do this, though if I really want it, I can get another GT51 for the starboard side like 2 Little Time. In truth, I've never used the side-scan. I spend most of my time fishing in pretty deep water where the structure is only the bottom contours. I'd much rather have a clear sonar picture at cruise than side scan any day.

2 Little Time: can you still see fish at cruise speeds?

Your present location does appear to be quite close to those 2 thru-hull valves. If you move it over, you should get a much more clear down view but an obstructed side-scan on one side due to the keel. If you can live with that, great. The only alternative is to mount a pair of GT51's on both sides of the keel. As I mentioned earlier, I went out yesterday and took some measurements. I have yet to look at bilge access since the boat is buttoned up with shrinkwrap. I won't know exactly where I am going with this until spring. If I pull the smaller deck panel located under the bench seat it should get me where I need to go.
I did manage to fire up my new 1042xvs on the kitchen table and get the software updated and the Active Captain paired with my phone. Those little battery jump packs they sell everywhere now are handy. We are going into boat show season up here so maybe I can find a deal on the G2 Vision HD charts.I have an older G2 Vision card in my old Garmin 720S that I can also use. Not sure if the upgrade is worth it but I like the auto route feature which the stock Bluecharts does not have.

 

[everwhom]

Rustygaff: I've heard folks recommend that you shouldn't put a thru-hull transducer directly in front of a motor because it can disrupt the water flow and cause performance and/or cooling problems. In fact, I did press Grady on where I should put a thru-hull 'ducer on my 330 and they replied "Only that they not be placed in front of any engine props as that would likely cause cavitation issues" Since my 330 has twins, the keel mount is not an issue, but it may cause a problem on a single...

 

[everwhom]

By the way, I think I've decided to move the transducer off to the port side where my marina is recommending and hope that it fixes the issue. There are 2 thru-hulls forward of the current location (baitwell and sewage ejection) and even though they are somewhat off to the sides, they may be causing enough water flow disruption to mess up the image at planing speeds. Also I'm realizing that the current location at the lowest point of the boat is probably a slight safety issue in that hitting a rock would likely break off the ducer and leave me with a pretty big hole in my bilge!

Unfortunately I won't know the result of the change until late April when I splash her for the season.

 

[Rustygaff]

Rustygaff: I've heard folks recommend that you shouldn't put a thru-hull transducer directly in front of a motor because it can disrupt the water flow and cause performance and/or cooling problems. In fact, I did press Grady on where I should put a thru-hull 'ducer on my 330 and they replied "Only that they not be placed in front of any engine props as that would likely cause cavitation issues" Since my 330 has twins, the keel mount is not an issue, but it may cause a problem on a single...

My transducer will most likely end up about 3 feet forward of the transom. I do not plan to use a fairing so the profile will be minimal.

 

[everwhom]

Change of plan. May actually try adding the fairing block so the transducer is further from the hull (and leaving in the same place)...

More details to come.

 

[wspitler]

I have a big thru hull Airmar 1KW (not sidescan) mounted about the same distance from the transom as yours, but well to the starboard side. Actually about 6 inches to starboard of the first starboard stringer. Just forward of the diesel tank. I get good readings at all speeds. There is a very good primer on transducer placement at sternmate.com that talks about all of the options and best practices. I have a GT51-TM transom mount on my Scout and used their (Sternmate) glued product to allow adjustment and eliminate any drilling into the transom Worked great after two minor adjustments and sea trials. The GT51-TH protrudes quite a bit more than my round Airmar, so that could be an issue if placed directly in front of a prop. If I go sidescan on my 330, I think I'll go with the transom mount between the engines. Good luck!

 

[everwhom]

wspitler: thanks! Yeah, my marina is concerned that the GT51 is pretty big so placing it right in front of the prop may create some problems. I purchased all my electronics from Gil Travis or Semper Fi fishing (he's a proper dealer, but sells only online through The Hull Truth), and he seems to be a pretty widely recognized expert on transducers... I spoke to him on the phone last night, sent him a bunch of pictures, etc, and he felt the problem is that my transducer needs to get into cleaner water, and we should try adding the full factory fairing block to push it lower.

I figure it's the easiest thing to try (no need to drill a new hole and patch the old), so may as well see if that solves the issue... If not, will be back to the drawing board next season, probably with a 2nd transducer since my system can run 2!

 

[Bg56126]

Reactivating this thread for a question. I’m looking at a 33 Express which has the thru hull mounted midship just aft of the door to the head. I’ve been around boating a while and never seen a mount this far forward. I know someone else in the thread said a VP at Grady told them to mount there but to me it seems to far forward to function in rough conditions. Is this really a recommended mounting spot?

 

[JosephC]

Reactivating this thread for a question. I’m looking at a 33 Express which has the thru hull mounted midship just aft of the door to the head. I’ve been around boating a while and never seen a mount this far forward. I know someone else in the thread said a VP at Grady told them to mount there but to me it seems to far forward to function in rough conditions. Is this really a recommended mounting spot?

Did you buy the boat? Does the thru hull transducer mounted in the cabin bilge area work while the boat is running? I just got a 33 Express with a transom transducer and I want to replace it with a thru hull. The electrician is recommending installing in the cabin bilge outside the raw water and bait well intakes so that the transducer does not interfere with the flow of water to the engines but I am not sure if the transducer will work well that far forward.

 

[Rcallum]

Did you buy the boat? Does the thru hull transducer mounted in the cabin bilge area work while the boat is running? I just got a 33 Express with a transom transducer and I want to replace it with a thru hull. The electrician is recommending installing in the cabin bilge outside the raw water and bait well intakes so that the transducer does not interfere with the flow of water to the engines but I am not sure if the transducer will work well that far forward.

Hi, I have a B164 50/200 installed in that same location now and it works okay, but not great. I would like to add a Chirp H/W transducer and wasn’t sure of the best location. Based on reading the thread there are a few different options. What did you end up doing? Thank you in advance..

Rodney

 

[Bg56126]

Did you buy the boat? Does the thru hull transducer mounted in the cabin bilge area work while the boat is running? I just got a 33 Express with a transom transducer and I want to replace it with a thru hull. The electrician is recommending installing in the cabin bilge outside the raw water and bait well intakes so that the transducer does not interfere with the flow of water to the engines but I am not sure if the transducer will work well that far forward.

I didn’t buy that specific boat but ended up with another 330. In mine my transducer is on the starboard side of the centerline just forward of the genset. Much like others in this thread have noted. I’m actually getting my electronics redone this winter by True North Marine here in CT. They are great and have done all my electronics over the years. We’re doing twin Garmin 12 inch and a new throughhull transducer that he recommends putting in the same spot.

here is a shot of the transducer. It’s hard to tell but it’s on the starboard side.