Mounting Downrigger Hardware Advice

ATPNW

Hello,
We recently purchased a Caper Cruiser 23', and are trying to get it prepped for the upcoming fishing season. We purchased Burnewiin Mounts to place on the gunnels. My questions are:

1. When drilling the 4 screw holes for the gunnel mount. Should I be using the technique where I drill a larger hole, fill with epoxy, and then drilling the correct size hole for the hardware?

2. When using the hole saw, there will obviously be a hole left in the gunnel. Should I be applying silicone to the hole that is left before inserting the mount?

This is our first balsa cored boat, so i am wanting to make sure everything is done correctly the first time.

Thanks,

Desert Dory

T.R. Bauer · Posted: Wed Feb 24, 2021 9:21 pm Post subject:

It always is better to over drill and fill with epoxy, but I don't feel that is a hard and fast rule like it is below the waterline.

robhwa · Posted: Thu Feb 25, 2021 11:15 am Post subject:

Definitely don't use silicone...it is hard to get off. If you drill, gouge (remove some balsa inside), fill with epoxy, and redrill you won't have a path for water to get into your core.

I use a Dremmel with a cutter wheel the size of the drilled hole, some people put an allen wrench, which also works. The idea is to get a larger solid expoxy area to redrill.

You won't need sealant, but when you do, don't use silicone if you ever want to get it off again, or replace it after it wears. Butyl tape sealant does the job, and is removable. It'll also make a neater job and maybe distribute the weight a little more evenly.

Do make sure you back the mounting underneath (other side), at a minumum with oversize washers (fender washers), or better yet, get a piece of strap aluminum from a hardware store and cut to distribute the weight over a greater area than the bracket covers above. Underneath will be where your greatest stress will be, and that stress can be huge when you hang on something.

robhwa · Posted: Thu Feb 25, 2021 11:28 am Post subject:

...since it is available, definitely get the BP620 backing plate as a minimum, but, in my opinion, it might not distribute forces across enough area that it won't stress things. C-Dories are built lighter than most boats (CD22 is 2000 lb for a 22 ft cabin boat). My father's 18 ft crabbing boat was built "like a tank", and weighed more. No cabin either. Maybe the Venture is beefier than a CD22. It is 1000 lbs heavier. There was a standard downrigger mount like this one on my original boat, and the fiberglass had "star" cracks from the stress. I'd probably make a custom part that is 2 or 3 times the length of the one you purchased if I could to better distribute the forces from your downrigger.

ATPNW · Posted: Thu Feb 25, 2021 1:02 pm Post subject:

Thank you all for the replies. A couple follow up questions if I could ask:

When filling the void in the gunnel with epoxy what do I put below/under the gunnel to keep the epoxy from running through? Would duct tape do the trick?

Also I did purchase the backing plate. But if I were to make a larger one myself out of 316 stainless steel sheet. What sort of tool would I use to cut it?

I've never done much with metal before but assuming it would just be a trace and cut?

Thanks,

davidJ · Posted: Thu Feb 25, 2021 1:40 pm Post subject:

On my CD 19, there is a 3" plastic pipe that runs about an inch under the gunnel on the starboard side, it holds your engine controls and wiring. If your 23 has one your mounts will not fit. You can check under your battery hatch to see what you have one.

Mounts for downriggers and pot pullers need to be bolted down, so you will have to cut an access hole on the inside of the hull thru the liner and dig out the styrofoam to put the nuts and washers on. You can get access covers to cover the holes. On my 19 the gunnels are wider, so I was able to work around the pipe to install Scotty base plates and also a pot puller bracket. Your mounts look really nice, but I wouldn't want to cut a 2" hole on top of my gunnels

Over drilling and filling with epoxy is for under water application, use a good calk or bedding compound, that's what they do on sail boats, and they have a lot of brackets on their decks and your brackets are going to be staying on forever. You can check the photo albums to see what people are doing on the 22's and 23's.

ssobol · Posted: Thu Feb 25, 2021 2:34 pm Post subject:

starcrafttom · Posted: Thu Feb 25, 2021 3:10 pm Post subject:

Just my two cents. Over drill and fill as stated above. Use thru bolts and a backing plate. Steel is good but rust and alum is alright but bends if not thick enough. I like to use a think piece of star board. Does not rot rust swell or shrink. Easy to work with hand tools. I would also use 4200 to create a seal around the mounts. The back fill will keep water out of your core but you dont want water running down the inside and sitting. Also see where the water that is going to go down the 2 inch mount holes when your not using the down riggers. Is it going to run to the bilge or to your batteries? On to you control cables? Know where that water is going to. When you cut your 2 inch hole make sure its really tight to the pole part of the mount. If it can rock back and forth a 1/4 inch that is a lot of room for the side / down pressure of the down rigger to move. i would go with a solid mount for the downriggers my self.

I just read your post and you said burnewin mounts and I assumed for downriggers. If these are just for rod holders then a backing plate is not needed nor are thru bolts. I would thru bolt it but thats just me and knowing how hard I am on stuff. But if just for rods or a bbq or table then the screws will work. Still over drill and fill.

starcrafttom · Posted: Thu Feb 25, 2021 3:16 pm Post subject:

robhwa · Posted: Thu Feb 25, 2021 3:34 pm Post subject:

ATPNW · Posted: Thu Feb 25, 2021 6:38 pm Post subject:

davidJ · Posted: Sat Feb 27, 2021 3:02 pm Post subject:

Are you aware that all of the 100+. bolts and screws that are attaching things to your deck and cabin are embedded in calk. It doesn't make much sense to over drill, fill with epoxy and re-drill your bolt holes when the cleat sitting next to your mount is embedded in calk. But I still would seal the edge of the big hole with resin, but I still don't like putting a big 2" hole in the gunnel. I hope you can attach a pot puller to your mounting bracket most of us up in the San Juans do crabbing shrimping and salmon fishing, and usually we will get at least 10 crab and about 80 shrimp for every salmon and some times we can crab, shrimp and try to catch salmon all on the same day, but it doesn't happen very often. Your down rigger should have a pole holder mounted on it so you can set your 2nd mount far enough away from the first mount so you can pull pots over the side between your downrigger and your pot puller. You can check out my photo album for set up ideas. good luck.