Scotty Depthmaster DR on Hobie Adventure

I recently got a good deal on a Scotty Depthmaster 1050 downrigger (referred to simply as "DR" from here on out). Depending on your preferred setup, this model can be a challenge to install on a kayak. The purpose of this post is to describe how I mounted it to my Hobie Adventure. A similar approach should work on a lot of other kayaks, and even if you're not interested in this DR, you might find some of these ideas useful for mounting other things.

My approach is similar to that used by "pmmpete" on the NWKA newsgroup, as described here:

http://www.northwestkayakanglers.com/index.php?topic=11954.0

I especially like the fact that his setup keeps the DR close at hand---no contortions required to lower and raise the weight.

I'm not claiming a great deal of originality. However, I used different material and a somewhat different attachment method, so you might find this variation worth considering. If you have a Scotty mounting peg to sacrifice, my approach will only cost you a bit of pocket change, and it can all be done fairly quickly, with just basic tools and a heat gun.

I haven't had a chance to try it out yet, so I'll post again once I give it a test run (with lots of pictures of big fish, no doubt). But I can say that it is rock solid---not the slightest hint of play or wobble. And if it turns out that I want to move the DR forward, change the angle, etc., those sorts of modifications will be easy and cheap (cheapness is a recurring theme here).

My main idea was to use a Scotty deck mount that I had already installed inside the right-hand mesh pocket. In addition, something is needed to help the base resist twisting forces, so I added an attachment point inside the cup holder. The cup holder thing is the trickiest part, although I think it's easier than what pmmpete did. There are simpler alternatives, which I mention briefly at the end.

I used scrap pieces of "starboard", which is essentially UV-resistant cutting board material:

http://www.kingplastic.com/products/all-products/king-starboard-family/king-starboard/

For this project, I used 1/2" and 3/4" black starboard and a few small pieces of 1/4" white. All of these were bought cheap as scraps at a local Tap Plastics store. I've included a brief discussion at the end about working with starboard.

I've broken this up into the following 6 parts. Note that only the first 4 deal directly with the mount as constructed:

1) Base plate to Scotty mount
2) Cup holder mount
3) Completed base
4) Shorten DR boom
5) Alternatives
6) Working with starboard

Each of these is in a separate post within this thread, because there are a ton of pictures and I thought it would be clearer to split it up. And, besides, I need to beef up my number of posts.

1) Base plate to Scotty mount: I had previously installed a Scotty deck mount inside the right-hand mesh pocket. The deck mount includes a 1/4" piece of starboard as a backing plate. The plastic on the right-hand side of my Hobie is much thinner than on the left-hand side, so the backing plate is, IMHO, essential here (and a good idea in general).

As it turns out, this deck mount is ideal for mounting the DR base plate, although perhaps not exactly as you might envision. A long Scotty thumbscrew (3.25") comes with the DR (for use with the included rod holder, which I'm not using). Miraculously, the thumbscrew is just the right length to attach a base plate to the Scotty mount. So I cut apart a Scotty mounting post, yielding a plastic-encased nut and a mounting post stub. I drilled a 5/16" hole thru the top of the mounting post stub so the thumbscrew can pass thru. The nut goes on the bottom of the Scotty mount, holding the long thumbscrew (and thus the base plate) in place. I then cut out a base plate from 1/2" starboard (diagram included) and drilled a 5/16 hole in it, aligned with the post stub. Ideally, you want the post stub flush with the gunnel when fully seated in the Scotty mount---otherwise you might have to do some extra work to level the DR base.

2) Cup holder mount: I cut a 1.5"x8" piece of 1/2" starboard and, using a heat gun, bent it in the center to 90 degrees. Then I cut it to size, drilled a 1/4" hole on top and a 5/16" hole on the vertical face, and using a rasp, filed the back side so it fits snug against the cup holder. This is attached at the top to the baseplate. I also attached it to the cup holder itself, as described next.

As previously mentioned, the DR includes a long thumbscrew. The corresponding nut has a rounded-over plastic housing, which I sanded down so that it approximately matches the angle of the cup holder. I also sanded the edges so it's rectangular-ish. Then I cut 4 small pieces of 1/4" starboard (about 2"x4" each, trimmed significantly after assembly). These were heated and bent to match the curvature of the cup holder (as measured on the inside of the kayak). The nut was embedded inside of the 4 starboard pieces, so it's effectively encased in 1" of plastic. For this part, a picture really is worth 1k words, which is fortunate because it takes 7 pictures to tell the story (well, the last picture just shows the cup holder without the DR base mounted and a nylon bolt inserted).

2) Cup holder mount: Continued (more pictures...)

3) Completed base: Of course, the DR base needs to be mounted to the starboard mounting plate. Here's some pictures of the base assembly, including a couple photos showing it mounted to the kayak. Note that the boom will be angled forward at about 30 degrees.

3) Completed base: More pictures (it keeps hanging if I put too many pictures in one post...)

4) Shorten DR boom: I used two pieces of 3/4" starboard. One piece has a 2" wide "arm" that I bent to 90 degrees. The 2 pieces are sandwiched together, with a 3/4" hole drilled thru the center. The cut-off boom was inserted and the plastic pieces thru-bolted onto the boom stub. Note that I drilled the 3/4" hole at an angle, so the top of the arm is parallel to the base. And I'd strongly recommend bolting the starboard halves together before drilling, unless you've got some very strong clamps. I'd also suggest doing all of the bending, drilling, and bolting before trimming to final size. I left a 2" gap between the DR handle and the arm that holds the pulley, which seems to be plenty of space to prevent my knuckles from scraping when turning the handle. You'll need to make careful measurements before drilling to be sure the top of the pulley is centered, with respect to the DR spool. Speaking of the pulley, I cut that off so as to include slightly more than a 2" length of the boom. Two 1/4" bolts hold it securely to the plastic arm.

That's pretty much it. Attaching the base assembly to the kayak takes a minute (literally) and, as I noted before, it's solid as can be. If you have any questions, feel free to pm me.

4) Shorten DR boom: One last picture...

5) Alternatives: Instead of using a mounting point inside the cup holder, it would be much simpler to install a short rail on the gunnel behind the cup holder and attach the base to that (I believe pmmpete also mentions this option). The base would probably have to extend a little further towards the back, and I'd cut out a slot so it would fit over the rail. But rails are expensive, and I don't think I'd use a rail in that location for anything else, so this approach wasn't for me. An even simpler (and cheaper) alternative would be to modify the vertical piece of starboard so that it fits snugly into the base of the cup holder, and do away with the cup holder thumb screw/nut altogether. It wouldn't resist any upward force, but it really doesn't need to, since the Scotty mount is so solid. As long as it's a snug fit, it would prevent side-to-side motion, which is its essential purpose.

There are also several possible alternatives for the boom arm. For example, you could drill and bolt a solid 1.5" piece of starboard (instead of a pair of 3/4" pieces sandwiched together) to the boom stub, then attach a 90 degree arm to that (1/2" material would suffice for the arm). But it's rare to find scraps of 1.5" material, and it seems that the thick stuff only comes in white.

Finally, I'd like to replace the stock pulley with a pulley that can hang directly below the plastic arm. That would bring the line slightly closer to the side of the kayak, and I think it would look nicer. So far, I haven't found anything cheap that will work, but if/when I do, that's one modification I'll likely make.

6) Working with starboard: Using the high setting of a heat gun, it's easy to bend 1/4" starboard, and 3/8" is not too difficult either. At a thickness of 1/2", it gets a little trickier, but narrow pieces are still fairly easy. Bending a 2" wide piece of 3/4" thick starboard (the "arm" on the shortened boom) is not easy. You need to be patient when heating, and be sure that you only bend it once---after it goes past about 20 or 30 degrees, don't let it bend back or the plastic will seriously deform. So keep heating and testing to see if it seems bendable. When you think it is, bend it to 90 (it'll take significant effort) and immediately dunk it in water, which will freeze it in place (otherwise, you won't be able to hold it in position and it'll snap back, ruining the piece). I'd suggest starting with the thin pieces, and save the bend in the  3/4" beast for last.

Regular woodworking tools work well. For the edges, a rasp is great and coarse sandpaper is good too. But, avoid sanding/scratching the faces, since scratches there are visible and almost impossible to remove. I'd avoid white (unless it's out of sight), since scratches in that really show.

Since it is polyethylene, you should not expect to get a strong glue joint with starboard. Heat treatment with a propane torch (just a quick pass over the surface, avoid burning) is supposed to improve adhesion. Regardless, you still need mechanical fasteners.

I recently replaced the nuts and bolts with t-nuts and flat head machine screws. Now there's no protruding points for things to hang up on. Not really a big deal, but I think it's an improvement.