Thru-Hull location help?

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#1
I'm designing my new FF/GPS Radar and settled on the Simrad NSS 12 EVO3. My problem is I would love to do a 1KW thru hull Chirp Fishfinder. The Transom mounts are huge and with twin outboards I dont want to have isses. QUestion is has anyone placed a thru hull? Boat is a 265 Express. I'm thinking about getting the B175HW unit if that helps. It seems like there is room in the rear but would like some real world knowledge.
Also, anyone know why I have 3 sea-cocks? 1 is Saltwater washdown, 1 is live well and the third??????
 
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max366

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#3
I installed a Raymarine thru-hull on the stbd side about 6" from the transom, near the centerline. Worked great even at full speed. Unfortunately, I don't have a pic to show you but the next time I'm at the boat, I'll get one.
I changed electronics to Axiom units and now use a transom mounted ducer- right near the keel on the stbd side. I left the thru hull ducer in place.
FWIW, I initially tried a in-hull ducer, just to the side of the bilge pump. Didn't work anywhere as well as the thru-hull.
2004 265 Express
 

Fishtales

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#4
I went with a shoot thru ducer. Didn't need to drill a hole. I'm on the factor flat area inside the hull.

If the boat is on stands so any water in the bilge drains and the plug is out.... Spray that bilge down with Zep mold and mildew remover (get at HD) and wash the whole bilge out and let her drain. You'll be link new down there.
 
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#5
So a little further investigation reveled that the third hole is a Dometic A/C intake! Yeah go figure someone needed A/C in the cabin of a 265. So I think my new plan will be to rip out the A/C. Then move the Livewell intake to the starboard side in the A/C hole. That will leave the complete port area for thru-hulls?
 

SkunkBoat

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#6
So a little further investigation reveled that the third hole is a Dometic A/C intake! Yeah go figure someone needed A/C in the cabin of a 265. So I think my new plan will be to rip out the A/C. Then move the Livewell intake to the starboard side in the A/C hole. That will leave the complete port area for thru-hulls?
I'd put it flat on the centerline between them like mine. Won't have to angle it.
Also, I don't think having inlets one right behind the other is good?

I don't have AC but I have sweated thru a few summer nights to get an early start...and pretty humid overnight at the canyon in summer.
You might want to reconsider that one since you already have it? Does it work?

Do you have hot water tank too?
 

max366

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#7
On the CL flat would be ideal but it's thick there! Also, the outside of the hull is rounded at that point, so the ducer flange wouldn't fit flush with the bottom, potentially causing turbulence and making it difficult to seal.
Airmar has thru hull ducers that compensate for the deadrise. I used a B60-20 - which can accommodate deadrise to 24 degrees- and it's just about flush with the bottom- no fairing req'd- but even though it's on the angled part of the hull, it shoots straight down.
 
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PrinceofThieves

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#8
You can go either way with the b175HW - in the middle, before the bilge pump or to the sides before any of the other intakes. You do not want an intake with strainer in front of the ducer as it will cause disturbance. The B175hw will fit in the center, but you will have to grind a little bit of glass away for it to sit flush and then give that area some love with a little coregrip or any hull & deck putty and then embed the ducer in 5200. I did it on my 265 and it came out great, but if you are not comfortable doing that kind of work, then go to the sides. I wouldn't necessarily rip out the a/c (granted that is in good working order), instead you can put two elements (wash down and livewell) on one thruhull by using a dual port pump. Downside to this is you will have to add another pump to the mix to pull from the 2nd port and you will have low pressure if using the wash down and livewell at the same time. However, I did do this as well on my 265 and just switched the livewell off while using the wash down if it was on at the time. You actually have more real estate down there than you think, its just a difficult are to work in with ducers that size. I actually had 3 massive thruhull transducers down there - the B175 and 2 Raymarine Axiom Realvision thruhull ducers.
 

SkunkBoat

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#9
You are going with NSS evo3. I think if you want to use StructureScanHD you are going to need either a fairing block and mount the StructureScan transducer thru hull on the centerline(Can't mount a fairing block directly in front of motors) or you will need to mount it on the transom between the motors. There are CHIRP thru hulls like the B175 but they are not sidescan as far as I have been able to tell. (somebody please correct me if I'm wrong)

In my case, I have Garmin. I already had an old B744vl hanging down on the centerline. It works great with a GD24 "traditional" 50/200kHz sonar.
The 94xsv came with(i.e. FREE) a transom mount dual sidesvu/clearvu transducer(GT51), whereas a thru hull with fairing block would be an extra $800, which is crazy...
So my sidescan is on the transom between the motors. The sidevu doesn't work at all on plane and the CHIRP Clearvu isn't very good on plane. Both work great at trolling/"looking for the wreck" speed.

Ideally, I would add a B175LH to better use the chirp Clearvu on plane.
 
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#10
I went with a shoot thru ducer. Didn't need to drill a hole. I'm on the factor flat area inside the hull.

If the boat is on stands so any water in the bilge drains and the plug is out.... Spray that bilge down with Zep mold and mildew remover (get at HD) and wash the whole bilge out and let her drain. You'll be link new down there.
Fihtailes, that's one of the reasons the boat is out. Annual maintenance! Thank you.

 
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#11
I'd put it flat on the centerline between them like mine. Won't have to angle it.
Also, I don't think having inlets one right behind the other is good?

I don't have AC but I have sweated thru a few summer nights to get an early start...and pretty humid overnight at the canyon in summer.
You might want to reconsider that one since you already have it? Does it work?

Do you have hot water tank too?
Wow! The transducer you have looks just like the one I really want which is the B275HLW! Do you have any issues with cavitation of your outboards at all? Looks like they are tucked nicely between the two strainers!

As for the A/C no need for it here on the Central West Coast. Maybe Ill just cap it for now.
 
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