Author Topic: Two towfish prototypes - Maple Blundy and Razorback  (Read 4428 times)

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Offline Drifter

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Two towfish prototypes - Maple Blundy and Razorback
« on: October 27, 2009, 11:21:41 PM »

First - I'm new to posting here and I'd like to thank the host for hosting the SI forum, the code slingers for the software and the posters for all the information shared here.

I have a 1967 16.5' Boston Whaler Nauset that bounces like a cork with anything other than calm winds and glassy seas. My goal is to have a towfish that is easy to deploy, runs close to the boat and is stable enough to eliminate most of the effect of boat movement on the SI sonar capture. It will see most of it's use off the Florida Gulf coast in 20 to 40 feet of water in vicinity of the Cedar Keys. The first unit was made out of PVC, with maple wood on both ends and having only three stabilizer fins. The transducer mount was made so it could be removed and secured on a pole mount (similar to a trolling motor mount).


Maple Blundy rode a shelf for a week due to bad weather. During the down time I was thinking that I would prefer a towfish that would take up less room and be easy to deploy. Something that world work similar to trolling with a down planer. Redneck engineering applied to some aluminum bar stock produced a new prototype. This unit earned the name Razorback from a collision between the vertical stabilizer and my leg.


The first trip out, I had to add a 2 pound down rigger ball to get it down several feet on a short tether. The second trip out I added some incline to the front dive plane, added another pound of weight, reduced the diameter of the tow line and lengthened the tow bar to allow more range in shifting "the center of gravity".

The third trip out was too rough to run decent lanes without taking waves over the bow. Still, it got pretty decent sonar capture. Much better than I expected.


I was able to pull the towfish while grouper trolling with positive results.

I have a XHS 9 SI 160 T on order that will go on a new version of the aluminum towfish. The new "Razorfish" will have a larger, adjustable front dive plane and tail fins that fold forward for transportation.

Footnote: This is what you get when you have the transducer on a pole mount and turn it so the back of the transducer is pointed forward while recording ...

(PS ~~~ This forum's BBC code is a little different from what I'm use to, I hope the picture links work.)

Edit: Mar. 26, 2011 ~ Updated picture links from to
« Last Edit: March 26, 2011, 10:25:05 AM by Drifter »

Offline Jolly Roger

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Re: Two towfish prototypes - Maple Blundy and Razorback
« Reply #1 on: October 28, 2009, 04:04:54 AM »
Hi Drifter,
and welcome to the forum.
Nice pictures and a smart design. Keep us posted on your projects.

Regards from Germany / Harry

Offline Humminbird_Greg

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Re: Two towfish prototypes - Maple Blundy and Razorback
« Reply #2 on: October 28, 2009, 11:43:07 AM »
Excellent Drifter, can't wait to see the Razorfish!

Greg Walters at Humminbird

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