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  1989 Outrage 22 Whaler Drive with Twin Engines: Mounting SONAR Transducer

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Author Topic:   1989 Outrage 22 Whaler Drive with Twin Engines: Mounting SONAR Transducer
wjd posted 05-18-2015 11:32 AM ET (US)   Profile for wjd  
I am preparing to mount a transducer on my 1989 OUTRAGE 22 Whaler Drive. In previous threads, I have found that some posters have had reasonable success mounting a transducer 13-inches off the center line of the keel. This is not an option as I have twin outboards. Where is the best location to mount a Airmar P66 transducer? Should I consider a through hull installation where I would need to remove the inner skin and foam?
Hoosier posted 05-18-2015 09:59 PM ET (US)     Profile for Hoosier  Send Email to Hoosier     
My 23 Walkaround has twins and the transducer is mounted right on the centerline, between the engines, at the lowest point of the "V". It does not have Whaler Drive.
jimh posted 05-19-2015 03:33 PM ET (US)     Profile for jimh  Send Email to jimh     
On a Whaler Drive 22-foot hull with twin engines, I'd first try mounting an Airmar P66 SONAR transducer on the transom of the Whaler Drive, between the two engines.

I cannot imagine tearing apart a Boston Whaler Unibond hull to glue an AIRMAR P66 to the inner side of the hull laminate. That is not a worthwhile exchange in hull integrity for any improvement in SONAR. A P66 is a bottom rung transducer from AIRMAR. Maybe if you had a $900 AIRMAR transducer you could give some thought to cutting it into the keel centerline with a fairing block or something like that.

You might try the Whaler Drive transom location as a first choice. If that does not work well, then try mounting to the boat hull at keel centerline to the original boat transom, below the Whaler Drive. The only worry I have with that location is the transducer might create some turbulence for the propellers.

wjd posted 05-20-2015 12:54 AM ET (US)     Profile for wjd    
Thank you for the replies. I have followed your suggestions and mounted the transducer between the outboard engines. Jim--I, too, had great reservations about cutting into the bottom of the hull for unknown results. I will try the [transom] of the Whaler Drive first and go from there.
russellbailey posted 05-27-2015 04:52 PM ET (US)     Profile for russellbailey  Send Email to russellbailey     
I agree with Hoosier about between the engines.

I'll caveat that I found that when in very shallow water, like less than 5', my transom mount transducer got interference from the engine. I could test it by tilting the engines out of the water - no problem then. In the water, interference, whether off or on. I solved that by drilling a big hole through the boat, a little fiberglass work to seal the hole from the foam, and installing a tilted element SS264 transducer. That has worked very well. We run a lot in very shallow water at the coast.

jimh posted 05-28-2015 08:49 AM ET (US)     Profile for jimh  Send Email to jimh     
HOOSIER's recommendation for "between the engines" is the same as mine. however his experience is based on a boat without a Whaler Drive, and he recommended to install on "the lowest point of the V". On a Boston Whaler 22-foot hull with Whaler Drive, there is no "lowest point of the V" on the Whaler Drive. The Whaler Drive has a flat bottom.

I suggested first trying to mount the AIRMAR P66 transducer to the transom of the Whaler Drive. Let me explain in more detail the reason for my recommendation.

If the AIRMAR P66 transducer were mounted to the "lowest point of the V" of the hull, it would be several feet upstream of the propellers of the outboard engines and at a level that was just about even with the propeller shafts. To help visualize the relationship between the "lowest point of the V" on a Boston Whaler 22-foot hull, the Whaler Drive transom, and the outboard engine, see my illustration at

http://continuouswave.com/whaler/reference/images/propellerTest/ whalerDriveDimensions600x450.png

The level of "the lowest point of the V" of the hull is denoted in my illustration as the "keel." The illustration shows a single engine installation, but with twin engines the same shaft length is used. In a twin engine installation the propeller shafts of the outboard engines would be slightly higher as the engines may be mounted higher than shown in the illustration. (That engine is mounted at the lowest position.) The result is that the propeller shaft of the outboard engines will be closer to the level of the "lowest point of the V" on the hull by perhaps 1.5-inches. If a SONAR transducer were to be mounted there, it could cause some turbulence in the water. The turbulence in the water upstream of the propellers could affect the propellers, possibly resulting in a decrease in propeller performance.

If the SONAR transducer is mounted on the transom of the Whaler Drive, as I have suggested, the transducer will be five to six inches higher than the propeller shafts of twin engines, and will only be a foot or so upstream. Any turbulence in the water created by the SONAR transducer will be less likely to affect propeller performance as compared to mounting to the "lowest point of the V" of the hull.

Also, I have mounted SONAR transducers on the transom of the Whaler Drive of a 22-foot Boston Whaler boat, and have had good results with them, particularly with the Lowrance SKIMMER transducers. On the basis of that first-hand experience, I have made the recommendation to first try that location for a SONAR transducer.

It may occur that mounting a SONAR transducer at "the lowest point of the V" on the hull of a 22-foot Boston Whaler boat is a good location and suffers no problems with loss of propeller performance, but lacking any first-hand experience with that location, I cannot endorse it as a sure bet, best place to install.

RUSSEL' comments about his installation using

quote:
a tilted element SS264 transducer

which has been mounted into the hull of the boat and required some drilling and modification of the Unbond hull. This is exactly in line with my earlier comment about the relative value of improved SONAR performance, the cost of the transducer, and the modification of the hull. An AIRMAR SS264 SONAR transducer is a $900 transducer. The cost of the transducer and the potential of improved SONAR performance by using it are reasonable trade-offs for making a big hole in the Unibond hull of a Boston Whaler boat.

I do not find a similar return in improved SONAR performance will be had from trying to adapt an AIRMAR P66 to use as a shoot-through-the-hull transducer, and I don't think it to be worth the bother of making a big modification to the Boston Whaler hull. If one had to employ a shoot-through-the-hull transducer, there are probably better models than the P66 to use. The P66 is designed for transom mounting. I would not recommend trying to use a P66 for shoot-through-the-hull mounting on any boat, and particularly not on a Boston Whaler boat, whose hull design makes use of shoot-through-the-hull transducers a particularly difficult problem, other than in a few models where the hull was specifically built with a special area (called a putty box) for SONAR transducer installation.

msirof2001 posted 05-28-2015 12:55 PM ET (US)     Profile for msirof2001  Send Email to msirof2001     
With my 1995 Outrage 21, I have a 1995 Furuno FCV-582 CRT Fish-Finder. The unit is so large, so deep actually that to fit it in the center console, we had to use a spacer to move the plexiglass electronics cover outward 3/4". This was a unit that a lot of commercial boats used. At the same time, Whaler basically said that if I put a through-hull transducer on my boat, I'll void the 10-year hull warranty. So I got a Furuno transom transducer which is about the size of a #1 golf club (driver) and is not rounded, not rectangular but has angled edges. Sorry, I don't have the model#. All of my electronics were professionally installed. I can confidently state that my transducer is the weakest link and everything else becomes as poor as trhe weakest link. I can make out the bottom at 300-400 feet but it is not clear at all and very sketchy. I can't believe the CRT Furuno still works after almost 21 years of ocean pounding but I think it's months are probably numbered. I could be wrong. When it goes, I'm in the same predicament as the original poster. Since I now have a Simrad NSS GPS/Plotter, the logical next sounder would be the Simrad BSM-3 sounder module. It is CHIRP and obviously the transducer would have to go. I've noticed these huge transom mounted CHIRP transducers but am leary given most of my existing performance issues are because of the fact it is a transom transducer. What has gotten me excited lately are the Airmar "Pocket-Mounted" transducers. Essentially like removing a brick-sized hole in the hull and replacing it with a brick. This is nothing I would try myself. In my area, there is a well renound fiberglass guy/boat repair who does a ton of work on Whalers, including warranty repairs. My warranty is long gone. I talked to the guy who did much of the design of the BSM-3 and he was saying how well it worked with the Airmar Wide-angle CHIRP transducers. I would probably go for the pocket-mount solution myself because it is more powerful than the tilted element transducers today. All of what I said is not cheap but having all that power without a fairing block protruding given my deep-ocean needs makes sense to me.
jimh posted 05-28-2015 11:13 PM ET (US)     Profile for jimh  Send Email to jimh     
The AIRMAR broad bandwidth transducers designed to be used with Pulse Compression SONAR are very expensive. Some of them are $1,500. Again, at that price, and given the potential for very significant improvement in performance, a reasonable case is made for going to the trouble of modifying the Unibond hull of a Boston Whaler boat. But, again, that does not mean you can make that same case for a $120 P66 Transom Mount being used as a shoot-through-the-hull transducer.

I don't see any problem with cutting into the hull to install a sophisticated $1,500 transducer, but I do see a problem in doing that to install a $120 P66 that was never intended to be a shoot-through-the-hull transducer. That's why I don't recommend cutting apart a Boston Whaler boat to install a P66 as a shoot-through-the-hull transducer.

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