Gluing wood to non-flat inner hull (Marine-Tex?)

[Wee Venture]

I purchased a Garmin rudder feedback sensor that I need to mount to the inner transom on our R-31 next to the rudder. I don’t want to through bolt it to the transom so I was thinking to mount it on a stainless ell bracket screwed to to a block of teak which in turn is glued to the transom. I have read a previous thread comparing epoxy and 5200 for a similar application and have heard people recommending both.

An additional issue is that the fiberglass surface on the inner transom at that location is rough, bumpy and slightly concave. So there is not a nice flat surface to glue to. So questions:
1. Can teak be successfully and permanently glued if the natural oils are wiped off?
2. Is there a better material than teak? I thought of Starboard but I don’t believe it can be glued.
3. Has anyone used Marine-Tex for an application like this - to provide a flat surface to glue to? I have not worked with it but have seen great reviews.
4. If so, would the Marine-Tex alone provide enough adhesive properties to secure the wood? Or Marine-Tex first for a flat surface, then 5200? ...Or skip the Marine-Tex and use the West System epoxy with a fairing compound? (I have previously used this for repairing a small hole in a different boat.)

I have the wiring connection for the rudder feedback sensor all worked out so it is just the mounting method that I need to decide on. If you’ve done anything similar that worked (or that didn’t for that matter) I’d love to hear. Thanks!

John Bachelor

 

[NorthernFocus]

Marinetex will work, West system will work, 5200 alone will work if it doesn't have to be too thick. If you talking about concavity caused by the curve of the transom 5200 should be fine for a small block. I wouldn't bother with teak in that application.

 

[ixlr8]

If there is any gel coat where you want to glue your bracket mount, you are going to need to scuff it up good so anything you use will stick properly. This could be a good opportunity to smooth out the surface to make it a little flatter to get bracket mount to stick better.

 

[BB marine]

I have used 5200 to glue and attach items to decks and hulls. In most cases I'm using fasteners to make the attachment along with the 5200. Once 5200 has cured it sticks quite well. I don't use teak for an attaching backing plate especially if I'm glueing it. Teak has oil in it. The oil could possibly cause a poor adhesion surface. I prefer to use a small oak block or marine grade plywood if I'm glueing to the hull. I use West System epoxy. First saturate the wood with epoxy to encapsulate the wood. Once the epoxy is cured and the wood is completely sealed with epoxy fit the block of wood to the surface. Sand the area, sanding out all high spots and gel coal down to resin surface. Wipe the area down with acetone. Use West System Fiberglass Boat Repair Kit 105-K it comes with everything you will need. Mix the resin and hardener together and then start mixing the adhesive filler into the epoxy mixture until it is a thick paste. Apply a thick layer on the contact surface of the block of wood and then on the prepared area of the hull. Cut 4 pieces of masking tape to be used to hold the wood in place until the epoxy sets up. Push the block of wood into the prepared area moving the block of wood slightly back and forth, up and down to get air out. Apply the tape to hold the block in place. The block of wood is now part of your hull.

 

[Toucan]

I will add to what Brian says, regarding using an oak block. Wash surface of hull. Rough up surface and sand down high spots. Wipe with acetone. Outline block location with masking tape. I like the Scotch blue tape and will never use the beige masking tape again. Shape the block to fit and mark the back side with an "UP" arrow. Seal the block with epoxy. After the epoxy cures, wash the amine blush off with water and dry. Scuff the back side with sand paper and wipe with acetone. Wrap the outside edge with a layer of masking tape. Mix epoxy with colloidal silica to peanut butter consistency and put a big blob on the center of the block, tapering to the edges. Push the block onto the mounting location, squeezing out excess epoxy. Holding the block in place, scrape off the excess epoxy with a square cornered item (mixing stick, putty knife, screw driver, etc.). Hold the block in place with clean masking tape. After the epoxy has set, pull the masking tape off the block and hull, leaving you with nice clean epoxy free surfaces. Continue supporting the block with clean tape until the epoxy has fully cured or it will slowly slide downward a bit.

Barry Thompson

 

[trailertrawlerkismet]

I’ve used 5200 to adhere starboard to the interior hull. Most recently I did this in the starboard locker so I could then mount a galvanic isolator to connect between shore power and the charger/inverter. Works like a charm.

Jim

 

[Salty7]

I used 5200 to mount a board to the inside of a sailboat hull once so I could mount a battery charger. Worked perfectly. I applied the 5200, put the board in place and wedged it there so it would stay in place until the 5200 fully cured, which takes about a week, maybe longer in cold weather. It is probably better than epoxy in this type of application because there may be a little flex in the hull or transom and the 5200 is flexible enough to withstand that without detaching from the board. I sailed the daylights out of that boat for years in all kind of weather and that board never came off and the battery charger stayed very firmly affixed where I wanted it. I would put the 5200 in place as multiple lines about 1/4" thick and place your board on it, push on it and wedge it in place until cured.

 

[Kaptajnen]

I have the wiring connection for the rudder feedback sensor all worked out

John,

Can you share how you plan to route the wiring from the feedback sensor?

 

[Wee Venture]

Kaptajnen, I originally was going to purchase an additional Garmin adapter to interface the rudder feedback sensor with the onboard NMEA 2000 backbone. However, we have been doing a fair amount of cruising, with a planned trip from Seattle to Alaska this summer over several months, so we ended up installing a Smartpump for performance and reliability. The cable from the GRF 10 rudder sensor plugs directly into the ECU (Electronic Control Unit) which is an integral part of the Smartpump.

 

[Wee Venture]

Appreciate the replies! And I have one more fascinating thing to throw in the hopper here. I just ran across a posting on Tugnuts that I somehow missed on my previous search. On Feb 28, 2017, Desertug posted about gluing studs to the transom with Weldmount AT-4080. I did a web search for the product and the stuff looks like a great and simple go-to solution for a number of applications, including mine. Has anyone else used this who could report on how it has worked?

 

[BB marine]

Appreciate the replies! And I have one more fascinating thing to throw in the hopper here. I just ran across a posting on Tugnuts that I somehow missed on my previous search. On Feb 28, 2017, Desertug posted about gluing studs to the transom with Weldmount AT-4080. I did a web search for the product and the stuff looks like a great and simple go-to solution for a number of applications, including mine. Has anyone else used this who could report on how it has worked?

Looks like good stuff. I have used similar products for anchoring fasteners in concrete but never fiberglass. It should work for your application. I stay old school. Using wood as a mounting plate I prefer resin. That is how Ranger Tugs are built. Every anchor point has a wood product attached with resin. If you chose to use a non wood product like Starboard. Also a good choice (Jims method) The 5200 proven method would be a good choice. The key component to success is clean well prepared surface. If you choose using the Weldmount I suggest you do a trial run with it on the bench to see how it works and reacts.

 

[NorthernFocus]

...The key component to success is clean well prepared surface...

Just so. Most people don't realize that fiberglass resin exudes a waxy film even well after curing. Washing raw fiberglass with acetone is a more effective surface preparation than sanding. Gelcoat needs sanding but not raw glass.

 

[mjq1987]

The ship repair industry uses Click Bond (competitor to Weld Mount) extensively with excellent results. It's been a slow process, but even the Navy and Coast Guard are beginning to authorize its use under certain conditions. I wouldn't hesitate to use these products on the boat, but the adhesives are not that user friendly. They have a short shelf-life (6 months without refrigeration and 1 year with refrigeration) and are the most expensive part of the process. If I had a lot of studs or components to install all at once, I would consider going this route, but it's probably not cost-effective to attach only a few things at a time...and the cleaning/prep process is the same as would be required for the 5200 use.

 

[BB marine]

Just another thought about mounting the Rudder feed back sensor. You may be able to fasten directly to the transom. The transom rudder area is relatively thick. I'm sure the factory can give you a lay up thickness. Assuming it is a minimum of a 1/2" thick( My C26 is more then 1" thick near rudder.) and you are using a 1/8" thick L- Bracket. I would feel comfortable measuring 3/8" on a drill bit marking the bit with electrical tape. Have 4 mounting holes in your L-Bracket for 4) 1/2" #10 tapping screws. Locate the proper location for the sensor, sand level area, use the bracket as your template. Drill the 4 holes. Use a fair amount of 5200 on the back side of the bracket. Fasten it to the transom with the screws. That will be there forever. Easy, well sealed permanent installation.( Contact Ranger for transom thickness in the area you are mounting the bracket)

 

[Wee Venture]

Brian, thanks for the suggestion! It looks like that may be the simplest way of doing it. I can screw the stainless steel bracket directly to the transom with self tapping screws and pilot holes that don’t penetrate to the outside. Liberal use of 5200 should seal everything up quite nicely and ensure the bracket stays in place. I measure the transom thickness at just over 1” at the cutout for the rudder post. But then it hollows out a bit forming a depression before getting thicker again moving toward the starboard hull. It looks like the minimum transom thickness is approximately 1/2”. So I think I’ll fill in the depression with Marine Tex to create a smooth flat surface for the bracket, and then make sure my screws penetrate all the way through the filler and into the fiberglass.

Thanks to all who replied. I definitely got some ideas for future projects as well. The Click Bond / Weld Mount products in particular look like they could be extremely useful in the right application. I appreciate this forum!

John B