Anyone out there try a thru hull transducer mount before?

Let me first precipice this with saying the following:  I currently shoot through the hull and I am unhappy with it. I do not think it gives me the sensitivity I am looking for in open water downrigger trolling for kokanee and fishing bass in deep water.  It might be my FF (eagle 245ds) not being sensitive enough.

I am looking into upgrading into a humminbird 345c this year and have heard good things about it.  but I also do not want any degradation in signal quality so I've been thinking of going the same route as some of the guys do down south like posted here:

http://www.bigwatersedge.com/bwevb/showthread.php?t=4520

Here is a few pics of his setup








can anyone give me specifics on faults they see for this type of setup?  the obvious one is that there is a risk that the transducer will pop off and the hull will fill with water.  but if done properly this risk should be mitigated by goop/3m 5200 and an internal rubber gasket.

scratching up of the transducer is another one, but i notice the bottom of my current kayaks almost never have scrape problems right in the middle, they are normally on the stern edge. 

one other thing is this kayak will rarely see the ocean - its primarily a delta/bay and lake boat, as I do plan to have another boat specific to the ocean someday.

That type of transducer is designed to be installed in a rigid fiberglass hull. A plastic hull is going to flex and greatly increase the risk of leaking. I would never consider this style of install on a yak.

Driiling a big hole on the bottom of a yak...You're a "brave" man Ben! 

#1 - yes, i'm a bit brave but also a whole lot of stupid

#2 - i'm considering multiple options on my new FF install. 

I am also considering a rudder mounted transducer but worry a bit that the cone will not spot what is in front of me, only what is right below me or behind me.  also worried about that one for times when i pull the rudder up (usually while anchored so i get a more natural set)

i also want to try a true shoot-through-hull mount with the puck style transducer. 

problem is i dont think there is any way to just try them all out and get a free or nominal cost exchange.  i do know i don't like gooped in transducers and i think the foam puck is annoying and not sensitive enough.

if i was to exchange for the thru-hull style, would that also shoot through the hull decently if i was to try a foam puck?  then i could see if the signal appears good enough before deciding to drill a hole...

Shooting through the hull of a kayak will always reduce the sensitivity of a depth finder.  With that said, my Lowrance x515 has been able to track bottom in over 300' at Hell Hole reservoir and just recently over 200' at Tahoe (I didn't go out any deeper).  My Lowrance has a ton of power but on the other end it eats batteries like there's no tomorrow.  I believe the newer HDS series use a lot less power and provides greater depth and sensitivity.

Here's specs on my discontinued model:
http://www.lowrance.com/Products/Marine/Full-Size-Sonar-Fishfinders/X515C-DF/Specifications/

And the replacement for it:
http://www.lowrance.com/Products/Marine/HDS-High-Definition-System/HDS-5x-Multifunction-Echosounder/Specifications/

I would first try shooting through the hull with the Hummingbird and see if that gets to the depth you want before doing any drilling.

I was wondering if you supply more juice to the FF will the resolution be better or signal be stronger?  Last weekend I was without my rechargeable AA's so I tossed in 10 alkaline batteries (15V?) and the screen was much nicer looking.

i dont think its the juice since i use a sealed lead acid battery, like i said it might be the FF itself since the 245ds (188w) wattage is much lower than the one i'm looking to get (345c has 300w).

so just by upgrading the FF i might be getting a much better signal.  battery juice won't be a problem with me as I always carry spares.

Since i'll be doing a humminbird transducer exchange I want to make sure i choose the right one.  They won't let me exchange one once its been used.  If i was to get a thru hull transducer rather than the purpose built shoot through hull (puck style) one, should that be able to shoot through just as well as the puck style would be?

Not in a million friggin years would I do that. There are enough hazards OTW w/o creating another potential one.
Have you tried the sensitivity adjustment on your FF?
Is your TD glued down or does it sit in a small puddle of water inside the hull?
The hull of your kayak will flex, expand, and contract with temp changes. Couple that with the vibrations during transport and it's not a matter of if will it leak but when will it leak.

Quote from the guy who did the above install: "I would say that I may settle for a purpose built shoot-thru-hull installation with epoxy next time. Its a small sacrifice compared to drilling thru the hull".

also, the newer FF also has much better screen resolution, so that would make things look better as well.

it's not the depth that's a problem - its marking stuff at depth.  I normally have no problem getting to 200ft of depth, but after a certain depth I start to lose track of things, and feel that it is affecting my ability to mark fish as well.  Like i can mark a 1/4oz jig down to 25-30 feet, but after that it disappears on me.  

i also turned my sensitivity up to 100% on my DS but it just makes the screen cluttered with junk.  i have tried it anywhere between 75 and 100% but i just can't seem to find a sweet spot that works exactly like i want it to.

 my hat is firmly tipped to a man much braver than myself!  I hope I don't have to tip it in front of both eyes to keep from watching you swim your yak back to shore! 

i'm not really that brave.  i just have been thinking this over a while and wanted some input.  the guys down there have been using similar setups for a while (years) and have not specified any problems with the set up yet.

i had not thought of the flexing of the plastic hull so I would need to consider that as well before trying anything as crazy as drilling through the hull.

i did already ask hobie and they stated that doing this would not void my warranty straight out - but it would preclude me from any warranty claims that arise from the hole, like expanding holes, cracks that come from it, etc. 

one of the other things is loss of resale value - but thats not an issue for me as i plan to die in this kayak (and drilling a hole in the bottom will probably help me get there faster  )

OK, I understand a little better.  You actually want more screen resolution not power or sensitivity.  The Eagle is 240 x 160px.  The Hummingbird is 240 x 320px.  You have twice the pixels with the Hummingbird and theoretically should be able to see smaller marks with it.  The other thing to try is using either zoom or bottom tracking.  This will enlarge any marks in the area.  Here's an example.



On the left is a 4x enlargement on the bottom and on the right is the full water column.  The fish mark at 82' is more pronounced on the bottom track than the full column.  Also my Lowrance is 400 x 400px.  So if you want to see small detail get a FF with a higher pixel count.

OK, I understand a little better.  You actually want more screen resolution not power or sensitivity.  

i actually want a little bit of everything.

last year while downrigging, i would drop my ball (2 1/2lb ball) and lose track of it around 40 feet.  this was true even while not moving, so the ball theoretically should still have been in the scope.  i even tried to zoom in around where it should have been, but was unable to see it.  not sure why that was. pixelwise i would think it still should have shown up if the FF was able to find it.  in those times i'm able to mark bottom but it is not a very good image, usually does not show any sort of contour.   I didn't have the same problem with my 565 mounted through my scupper hole on my T13, only with the DS.  of course the 565 also has higher screen resolution, but it also didn't have to shoot through the hull.

also, trees and fish are apparently interchangable to the FF.

I guess part of it is i'm about to drop a good chunk of change on a FF and I want to get my money's worth out of it.

OK, I understand a little better.  You actually want more screen resolution not power or sensitivity.  

i actually want a little bit of everything.

last year while downrigging, i would drop my ball (2 1/2lb ball) and lose track of it around 40 feet.  this was true even while not moving, so the ball theoretically should still have been in the scope.  i even tried to zoom in around where it should have been, but was unable to see it.  not sure why that was. pixelwise i would think it still should have shown up if the FF was able to find it.  in those times i'm able to mark bottom but it is not a very good image, usually does not show any sort of contour.  

also, trees and fish are apparently interchangable to the FF.

I guess part of it is i'm about to drop a good chunk of change on a FF and I want to get my money's worth out of it.

I use an Eagle 245 with the stock transducer sitting in a cut-out pool noodle with a puddle of water in it (ie transducer not glued to the hull). I can see my 2 oz and 3 oz rf jigs go all the way to the bottom in depths up to 50 feet, and heavier jigs down past 100 feet. I might be able to see little jigs deeper than 50 feet but I've never tried fishing any deeper than that with such light jigs.

My finder was only $125 and I use 10 AA batteries. If you're having trouble seeing a 2.5 lb ball past 40 feet then the trouble is with your installation. Using water instead of gooping your puck down ensures a consistent solid material between your puck and the water outside every time. This also means no extra holes below the water line.