cutting deck

[ssobol]

I am looking to cut a hole in the aft deck of my Zodiac Pro II 470 to put in an access plate so I can get into the hull to mount an in-hull transducer for a depth finder. It would be just forward of the sump at the very back of the deck (the sump is at the transom/deck join).

Anyone have any idea how thick the deck is in this area? What would be the best way to cut the hole (4" dia.)?

Thanks.

 

[jondavies]

Re: cutting deck

I can't answer your question directly but I'm wondering if there's there a big advantage to an in-hull transducer vs. a transom mounted one?

I know it's cleaner to have the TD inside and there's less risk of it getting damaged but for me, those benefits would not be outweigh the possibility of compromising the structural integrity of the boat and/or decreasing its resale value.

 

[ssobol]

Re: cutting deck

I haven't done anything yet, I am just considering the options. However, it would be useful to know the depth of the water I'm in.

I realize that there is some risk in cutting into the hull and I don't particularly want to do it. However, looking at the back of the boat there doesn't seem to be a good place to put it on the transom. From my understanding it needs to go on the right side of the engine due to the prop rotation and be as far away as possible while still being in undisturbed water.

Between the self bailer drain opening and where the bunks land when the boat is on the trailer, there doesn't seem to be a good place to put it on the transom. I don't have a unit yet so I don't know for sure how much space it will take, but I have read some of the manuals for different models to see how they need to be installed.

As it happens, (seen from the outside) there is a flat spot at the rear of the hull on the centerline of the boat (deepest part of the hull). At first glance this spot seems a perfect place to put a transducer on the inside of the hull. However, there is no access to the inside of the hull except for two small drain ports (normally plugged). One from the deck sump to the inside and one at the bottom of the transom that drains the hull.

I have tried looking in through these openings but they are too small to really see anything.

 

[jondavies]

Re: cutting deck

I know what you mean. I had the same dilemma when I was placing the TD on my boat (though mine's a SIB so in-hull was not an option). I ended up putting the transducer about 2/3 of the way between the keel and the tube.

I get a good signal at slow/medium speeds but it often cuts out when I go above about 20 mph. I suspect that's just a function of a soft hull. I mostly use my boat for diving so I don't care much about sonar readings at speed.

You might try rigging up some kind of temporary TD mount (2x4?) clamped to the transom and see what kind of readings you can get externally before cutting the hull.