I am about to drill a 2" hole to install a depth/speed transducer, and wondering what I might find. is it solid or cored beneath the v-berth?
thanks ...
thanks ...
drilling holes thru the hull ...
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I don't know for sure, but you may be able to deduce it's construction from my experience. Because of the negatives of a through-hull (increased drag, hull integrity, compromised strength) I decided to go with an in-hull in the same location. I gave up signal strength, but it seems to work okay when depth is less than 50 feet.
An in-hull will not work on a cored hull. There can be no air where the signal shoots through. Because my in-hull works, I can only assume it is solid, not cored, in the place where you want to mount.
By the way, I mounted mine just a bit off center. The surface had to be a flat plane, and the center "V" of the hull wouldn't work and probably is too thick anyway.
Note: My hull was laid in 1977. I don't know if Catalina changed their hull construction technique between years.
Jon
I have a couple of through holes 4 the transducer and odama tre that are just in front of the motor. I had an inboard transducer that came with my garmin that I mounted nearby with beeswax. It seems to be working just fine.
"decreased hull integrity and compromised strength"?
Uh... no I don't think we can let that one get passed.
Has anyone ever (and I mean EVER) heard of a hull losing integrity because of a 2 inch thru hull with a transducer in it?
If so, I'd really like to hear about it.
Also, your boat is made of FRP. This is fiber reinforced plastic. Plastic thru hull does not reduce hull integrity in any way.
Also, to suggest that a thru hull transducer adds anything close to a measurable drag on the boat is bad information.
Walk through any boat yard near you and look at any serious race boat (J-boat, Melges whatever) and look at how many thru hull transducers you spot. If these guys are not concerned with the "added drag" then you can be sure it's not an issue.
Your hull is solid. Not cored.
Go ahead and drill baby drill!
T
Uh... no I don't think we can let that one get passed.
Has anyone ever (and I mean EVER) heard of a hull losing integrity because of a 2 inch thru hull with a transducer in it?
If so, I'd really like to hear about it.
Also, your boat is made of FRP. This is fiber reinforced plastic. Plastic thru hull does not reduce hull integrity in any way.
Also, to suggest that a thru hull transducer adds anything close to a measurable drag on the boat is bad information.
Walk through any boat yard near you and look at any serious race boat (J-boat, Melges whatever) and look at how many thru hull transducers you spot. If these guys are not concerned with the "added drag" then you can be sure it's not an issue.
Your hull is solid. Not cored.
Go ahead and drill baby drill!
T
Ah, hang on.
First, OF COURSE there is lowered hull integrity with a thruhull. By pure engineering definition, complexity lowers reliability. Putting a hole in a solid piece of GRP and plugging it with mastic, and a bunch of plastic clearly lowers the hulls reliability (integrity). Lots of sailors avoid thruhull for this reason.
Now is it an acceptable risk? I think so. Most people do. But it does lower the integrity of the hull.
Also there IS a drag issue with standard thruhulls. Look at those J and Melges or 36.7s closely and you will see that 95% of the owner went to considerable expense to have flush thru-hulls inserted. These require careful beveling of the GRP to match the thruhull. An expensive job. The standard ones have lips that disturb waterflow over the hull.
I've got no issue with thruhulls. I suggested the OP to drill away. But lets present all of this fairly.
The Airmar P-79 type in hull transducers perform exceptionally well, are easy to install, significantly easier to align properly and there is never a potential for a leak around the thru-hull fitting..... They are available for most sounders.
Our boat is still on the original Radarsonics 200kHz transducer that was glassed inside the hull in 1979. This transducer has been through no less than six depth displays over its 33 year life and is currently feeding a 2010 Raymarine ST-60+ depth. I also have a back up P-79 installed and ready to go in the event that the 33 year old Radarsonics transducer fails.
With a solid glass hull I much prefer the P-79 and repairs can be done in-water when they do fail and you save the cost of a short or long haul.. This alone more than makes the P-79 an excellent choice.....
Our boat is still on the original Radarsonics 200kHz transducer that was glassed inside the hull in 1979. This transducer has been through no less than six depth displays over its 33 year life and is currently feeding a 2010 Raymarine ST-60+ depth. I also have a back up P-79 installed and ready to go in the event that the 33 year old Radarsonics transducer fails.
With a solid glass hull I much prefer the P-79 and repairs can be done in-water when they do fail and you save the cost of a short or long haul.. This alone more than makes the P-79 an excellent choice.....
Dry Run ............
Good luck and let us know how it works.
Why not give it a dry run before drilling any holes which aren't needed ? Fill a Zip-Loc baggy baggy with water, seal it, place it where you intend to mount the depth sounder, place the transducer on the bag of water, and see what kind of a reading you get. If your hull is not is not cored, you should get a good reading. You're then ready to mount sans hole.
Good luck and let us know how it works.
I am in no way saying that going through-hull is wrong. It just wasn't my first choice.
First, the mounting location. The OP wants his under the v-berth which is where I wanted mine, too. Having it forward of the keel meant drilling a hole in one of the strongest and thickest places in the hull. I wasn't comfortable with that.
Second, also related to strength. If one were to hit an object while underway, it will most likely be forward of the keel. Again, having a piece of plastic where thick fiberglass used to be in the potential strike zone - I wasn't comfortable with that either.
Third, leakage. Most through-hull transponders work fine. If there will be a problem with leakage it would likely present itself in the first weeks or months after installation. However, because of travel, my boat is in the water at the slip for months between visits. In other words, my bilge and batteries would may have to stay on top of any leaks for a long time before I would discover it. Low probability, but still I wasn't comfortable with it.
Fourth, is complexity as Jackdaw describes. The fewer holes in my hull the better. I don't even have a propeller shaft - it's an outboard model. Every type of through-hull has to be periodically checked for leaks. This includes through-hull valves, propeller shafts, and transducers. The only through-hull fittings I presently worry about are valves. It does not mean a through-hull is a wrong decision, it means it was not my first choice.
Fifth, low risk and cost. The supplier of my transducer couldn't have been nicer. If the in-hull didn't work or even work well enough to satisfy me, he said I could return it for full credit towards a through-hull transducer. Given that assurance, it made sense for me to try the in-hull option first before paying for a haul-out and drilling another hole in the hull.
Lastly, Jackdaw is correct that "lots of sailors avoid thru-hulls". Although we can't quantify this, the market is large enough to justify alternatives to through-hull transducers. There are both in-hull and transom-mounted options. The manufacturers would not waste resources producing products if there were no market.
In the interest of civility, let's try to keep the histrionics in check.
Note: This post was responding to posts that have since been removed.
First, the mounting location. The OP wants his under the v-berth which is where I wanted mine, too. Having it forward of the keel meant drilling a hole in one of the strongest and thickest places in the hull. I wasn't comfortable with that.
Second, also related to strength. If one were to hit an object while underway, it will most likely be forward of the keel. Again, having a piece of plastic where thick fiberglass used to be in the potential strike zone - I wasn't comfortable with that either.
Third, leakage. Most through-hull transponders work fine. If there will be a problem with leakage it would likely present itself in the first weeks or months after installation. However, because of travel, my boat is in the water at the slip for months between visits. In other words, my bilge and batteries would may have to stay on top of any leaks for a long time before I would discover it. Low probability, but still I wasn't comfortable with it.
Fourth, is complexity as Jackdaw describes. The fewer holes in my hull the better. I don't even have a propeller shaft - it's an outboard model. Every type of through-hull has to be periodically checked for leaks. This includes through-hull valves, propeller shafts, and transducers. The only through-hull fittings I presently worry about are valves. It does not mean a through-hull is a wrong decision, it means it was not my first choice.
Fifth, low risk and cost. The supplier of my transducer couldn't have been nicer. If the in-hull didn't work or even work well enough to satisfy me, he said I could return it for full credit towards a through-hull transducer. Given that assurance, it made sense for me to try the in-hull option first before paying for a haul-out and drilling another hole in the hull.
Lastly, Jackdaw is correct that "lots of sailors avoid thru-hulls". Although we can't quantify this, the market is large enough to justify alternatives to through-hull transducers. There are both in-hull and transom-mounted options. The manufacturers would not waste resources producing products if there were no market.
In the interest of civility, let's try to keep the histrionics in check.
Note: This post was responding to posts that have since been removed.
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