In-hull transducer question

[TBird]

I just bought a DSM30 and am ready to take on the fish finder installation project. I have searched the forum re: transducers and am still unclear about whether an in-hull transducer (such as the Airmar P79) will work. I would prefer not to go throught the hassle of hauling the boat and installing a thru-hull transducer if it can be avoided.

Has anyone had success with an in-hull? I've read that I may give up 20% of the performance relative to a thru-hull; I am willing to live with that if I can avoid the hassle of gettin the boat hauled.

Also, I don't think my hull is solid fiberglass (but I am not sure). Is that a big problem with the in-hulls? Do I need to take out a layer to get down to the fiberglass? Thanks for your feedback.

 

[Sundancer]

The best bet is to look around the bottom of your boat to find a spot that looks good. When you have it all hooked up, put the transducer in a zip lock bag full of water and move it around until you find a spot that seems to work. You can also check with Sea Ray to see if there is a spot they would recommend. On my boat I see spots that are reinforced for a through hull. Those are where I would start, but try other areas as well. It should be good and solid transferring the sonar with little loss. Once you find that spot, make sure you check it on plane to make sure there aren't any air bubbles produced by the hull. Epoxy it in place and you are all done.

 

[Alex F]

I just bought a DSM30 and am ready to take on the fish finder installation project. I have searched the forum re: transducers and am still unclear about whether an in-hull transducer (such as the Airmar P79) will work. I would prefer not to go throught the hassle of hauling the boat and installing a thru-hull transducer if it can be avoided.

Has anyone had success with an in-hull? I've read that I may give up 20% of the performance relative to a thru-hull; I am willing to live with that if I can avoid the hassle of gettin the boat hauled.

Also, I don't think my hull is solid fiberglass (but I am not sure). Is that a big problem with the in-hulls? Do I need to take out a layer to get down to the fiberglass? Thanks for your feedback.

TBird,
I did this project about a month ago and went with B60-20 ducer. I don't think you have an "emergency", b/c SmartCraft should give you depth reading on the tachs, I've used it for 2 seasons and finally gave up and proceeded with the installation of DMS30 and B60-20. So, why don't you wait until next houl out and address it then? IMO, your core is solid fiberglass, just like mine.

The following links will help you if you decide to go with thru-hull ducer.

Here's Vince's thread with picture of what I consider solid fiberglass hull, mine is the same and your '07 340DA should be the same, but you might want to double check.
http://clubsearay.com/forum/showthread.php?t=14626&highlight=transducer

Here're links to 2-part video Jim (site owner) put together:
http://www.youtube.com/watch?v=QcBdkjCtifA

http://www.youtube.com/watch?v=nd-RPx34nUE

 

[Henry Boyd]

Tbird,

In answer to your question, yes the in hull transducer will work. A friend has one on his tuna boat. BUT, it is not without aggravation. These things require a mineral oil bath to work. When the housing comes loose (as they all do) the mineral oil leaks out into the bilge. This creates a mess, and over time makes it impossible to re-adhere the darn thing back down. My friend by the way has converted to a through hull set up.

Henry

 

[teddiamond]

Thanks that makes one thing clear on my install of a Lawrance 525C. One other question what would be the best route for the cables from engine room to under dash?

Thanks in advance

Ted:smt100

 

[Lazy Daze]

I don't know the construction of your hull. BUT, if your bilge floor is finished gelcoat (like the topsides - very straight and smooth), then it may be VERY difficult to get it to work as there can be voids between the inner liner (finished gelcoat) and the outer hull.

If your bilge floor is not totally smooth and looks more like a thin layer of paint (actually gelcoat) sprayed over fiberglass, then it should work.

However, seeing as your boat is a newer one, I would lean towards thinking your boat uses the inner liner technology.

 

[Alex F]

Thanks that makes one thing clear on my install of a Lawrance 525C. One other question what would be the best route for the cables from engine room to under dash?

Thanks in advance

Ted:smt100

I think this would apply more to OP's 340DA, but it may work for you as well.

 

[TBird]

I don't know the construction of your hull. BUT, if your bilge floor is finished gelcoat (like the topsides - very straight and smooth), then it may be VERY difficult to get it to work as there can be voids between the inner liner (finished gelcoat) and the outer hull.

If your bilge floor is not totally smooth and looks more like a thin layer of paint (actually gelcoat) sprayed over fiberglass, then it should work.

However, seeing as your boat is a newer one, I would lean towards thinking your boat uses the inner liner technology.

Thanks for the advice. Does it make sense to try to remove the inner liner if it exists? I'm really trying to avoid a thru hull.

 

[Lazy Daze]

Thanks for the advice. Does it make sense to try to remove the inner liner if it exists? I'm really trying to avoid a thru hull.

Hmmm. Good question. Right up front - I can't answer that with any certainty. However, I do think it's possible... but at what cost is the question. I don't know how much fab work/shoring up would need to be done around the hole. My gut tells me it would be easier just to haul it out; or do it when you are pulling out for something else.

If you were able to proceed, the next variable would be making sure you drill/cut out the hole from ONLY the inner liner and don't go all the way through. :wow:

 

[fouroaksphoto]

I fabricated a transducer housing out of 4" PVC pipe, suspended the transducer in the pipe, filled the pipe with mineral oil, ran the ducer wire through a rubber boot and clamped it to the top of the pipe. The pipe is secured to a flat area in the bilge using only 3M 4200 Fast Cure Adhesive. All the parts came from Lowe's plumbing section. I can easily remove the ducer if I have to or the entire unit for that matter. I get excellent depth soundings and incredible sonar bottom detail at 70' (as deep as it gets here) and never lose the signal in rough water or in tight turns. If your hull has no porous layers this should work for you. I can send pics if you wish and construction details via private message if you wish. I love this setup and nothing is epoxied to the hull nor did I have to cut through the hull. Hope this helps.

 

[flarepoman]

I put the in hull transducer. With the DSM300. Works like a charm. No leakage. Just clean the inner surface real good. Take your time. I will however put a through hull next haulout.

Rick