drilling holes in my boat

[fishnutt]

I just purchased a new gps combo,I will be mounting the transducer on the transom, I am a little skeptical about doing this,Any tips on doing it right the first time.

 

[Don S]

Re: drilling holes in my boat

Assuming it's a fiberglass hull, When you drill the pilot holes for the screws, be sure you seal them with marine sealer like 3M 4200 or 5200. Do not use silicone below the water line.

 

[BillP]

Re: drilling holes in my boat

Drill oversized holes and fill them with epoxy. Then drill (not all the way through) pilots in the center for the smaller transducer screws. This method seals the transom forever. Use poly or polysulfied if not doing the oversized hole method. They seal and aren't adhesive. If 4200 or 5200 is used you won't be able to remove the transducer later without great effort (and most likely destructrion)...they are adhesives.

 

[jeffnick]

Re: drilling holes in my boat

Drilling into your boat is one of the hardest things about boating, but done right, there's nothing to worry about.

I believe the 'epoxy' method is overkill.

Drill the correct sized and depth hole for the fasteners and chamfer the openings. Then run the screw(s) in the hole(s) and remove them. Now fill the hole(s) with 5200 using a syringe to fill from the inside out. Now mount your transducer.

This pic was taken while installing Bennett tabs, but you can see the hole with the well chamfered opening and the 5200 being applied from the inside out by the syringe.

If you don't chamfer the opening enough, you'll chip the daylights out of the gel coat when you run the screw in.

This is how I fill the syringe with 5200. You can get a syringe at WalMart Pharmacy or Tractor Supply or an animal hospital if your doctor or dentist won't give you one.

The small tube lets me put the 5200 into the end of the blind hole. If you've drilled all the way thru the transom, make sure the hole is filled up and the 5200 is running out the other side before putting in the screw.

If this is your first time, you might try practicing on a piece of wood or even an inconscicuous/inconsequential place on the boat. You don't want the hole so small that the screw breaks off when you run it in, and you want the chamfer big/deep enough so the gel coat doesn't crack.

Another option is to thoroughly clean the spot your going to use (first with soap and water, then with acetone), and 'glue' a piece of teak onto the hull with 5200, then mount the transducer on the teak = no holes in the boat. Here you can see I attached a piece of plastic to the transom using the existing holes, when I changed my transducer. I tried several positions before finding the right one -- without putting any new holes in the transom.

I've never had a problem removing screws that were bedded in 5200 and even things attached with 5200 can be removed if you can get a piece of dental floss, or piano wire under an edge.

 

[QC]

Re: drilling holes in my boat

Good stuff above, but like DonS mentioned, you should clarify if this is a Fiberglass, Aluminum or Wood boat . . . 5200 on all three, but I'd seal fresh drilled holes with Epoxy on a wood hull first. Aluminum will need to be thru-bolted.

 

[BillP]

Re: drilling holes in my boat

You will not find a pro marine tech on the planet that uses it for installing tranducers, thru hulls or any accessory that may need to be removed later. 5200 is good stuff and ok but it continues to harden over time...which leads to cracking and letting water in. This is not opinion...but common fact and easy to verify if you ask restoration yards that work exclusively in replacing transoms, floors, stringers, etc. Early boats with decks originally set in 5200 at the factory 20+ yrs ago (when it was the miracle of all caulks known to man) are getting leaks below. They are finding the joint leaking from brittle/cracked 5200. I personally sealed a new transom/deck joint with 5200 in the mid 1980s and by the mid 1990s it was hard like a bowling ball and hairline cracked in places. The transom got wet and I had to replace it again...after that I did some research and learned.

If you aren't going to take the time to do oversize holes with epoxy, at least coat the holes with epoxy or thin superglue before doing caulk. The only time 5200 can be cut with floss/wire or remove screws is when it's young. Give it 5 yrs and it will be near to or impossible.

 

[BillP]

Re: drilling holes in my boat

oops double post...my pc is locking up after responding

 

[mattttt25]

Re: drilling holes in my boat

Have always been told, if you never want to remove it use 5200. If you may want to remove it use 4200.

 

[Boatist]

Re: drilling holes in my boat

I would mount one of the transducer mounting plates then mount transducers to it.
Go to "cabelas.com" the search for transducer mounting plate.
Pick the color plate your want and install the plate first then add the transducer.

I installed mine with no screws at all and it was that way for many years. It was just glued with silicon.
Later I added a very large 8 degree transducer and decided to change it.
My boat is Aluminum and the plate I used is also Aluminum 1/2 inch thick by 4 inches high and about 8 inches long.

The change I made was to remove the Pitot Tube and driled matching holes in the mounting plate.
Then got longer screws for the Pitot Tube. Sealed the Pitot screws holes with 4200.
Then as before stuck on with Silicon seal. Put on the Pitot tube with longer screws and then mounted
My 200 khz 20 degree transducer, My 200khz 8 degree transducer and a speed wheel.
Been on there many years now with no problems at all.

 

[erikgreen]

Re: drilling holes in my boat

Or instead of getting the "transducer mounting plate" from cabelas you can go to most lumber yards and get some plastic planking... pretty much the same stuff, you just have to mount the plank/plate carefully as noted above, then you can use short screws to attach transducers to your heart's content, the stuff is plastic so it won't rot.

Erik

 

[seven up]

Re: drilling holes in my boat

I'll go for any method that supports the transducer without drilling holes in the transom.

Had the same experience as mentioned above by Bill P only with the 4200 fast cure. The joint split/cracked in two years. The thickness of the joint was to the limit recommended by 3M, though.

What boat is this going on? A 60 foot Pacemaker ? Inflatable ? Drilling holes below the waterline brings "new transom" to mind.

 

[erikgreen]

Re: drilling holes in my boat

I should also put in - for the holes in my transom I follow the old standard - fill with epoxy, then re-drill the hole.

There are two potential problems drilling holes in the transom - the first is leakage around a through hole, which most people cope with well using washers, sealants, and bilge pumps.

The more dangerous one is saturation of a cored transom from water ingress. In that case, it's safest to do what the boat manufacturer would have done in the first place: Ensure that no core material can be exposed to water by fully encapsulating in plastic/glass. IE, pre-drill an overlarge hole, completely patch the hole with epoxy and filler (and possibly glass). Once that's done, you have a solid fiberglass patch to mount on. No worries about water ingress, unless you drill all the way through.

FYI, this sort of strategy can apply to any hole drilled anywhere on the boat through cored material - decking, interiors, anywhere.

That said, you can encapsulate your core material with whatever you want... on a sliding scale it goes something like:

chewing gum...silicone...waterproof glue...liquid nails...3m 5200...epoxy

So choose whatever as your sealant, just be aware of how long it will last, and know that you're supposed to check your hull penetrations and screw holes for leaks annually or whenever you pull the boat.

Erik

 

[Jack Daniels]

Re: drilling holes in my boat

I just purchased the plastic plate from cabellas, I dont want to drill into my transom at all. Should I just use 5200 to glue to plate to the outside or do you guys recommend anything else?

 

[dingbat]

Re: drilling holes in my boat

Nothing sticks to starboard. You will need to use some sort of mechanical joint between the 5200 and the plate.

I friend of mine cut two shallow dovetails in the back of the plate and filled them with 5200 and then attached the plate to the transom which worked well. I went the over size hole and epoxy route and just used the two mounting holes on the plate

 

[Jack Daniels]

Re: drilling holes in my boat

ok forgive me for being slow, so i just cant glue it to the transom. I really dont want to drill any holes at all. I dont care if the plate ever comes off tbh. I just want something that i can mount the transducer to and anything else i need to mount. If i were going to just install two screws to mount the plate i might as well just mount the transducer directly to the transome. Thanks for the help, do you think some sort of super epoxy will work with 5200 around the edges?

 

[dingbat]

Re: drilling holes in my boat

The problem is that the plate is just like teflon. Nothing really sticks to it.

Even if you end up drilling and using epoxy on the screws holding the plae on your still way ahead of the game over just mounting the transducer. I have 10 holes in my plate from past transducers, speed sensors and temp sensors.

I finally gave up on transom mount transducers and installed a thru hull but still have the speed sensor on the plate.

 

[BillP]

Re: drilling holes in my boat

If it bothers you that much mount it inside and let it shoot through the hull. Take the puck off the mount and set in silicone. You will lose temp and speed though.

 

[jeffnick]

Re: drilling holes in my boat

When you're using the oversize hole/epoxy method, how do you keep the epoxy in the (horizontal or blind) hole, and how do you know if it's all the way to the bottom of the blind hole. Also, I assume the epoxy method sould be used on the mounting bolts for the outboard or outdrive, but I can't remember ever seeing it used there...most are sealed w/ silicone or 5200. I can certainly see using the epoxy method for firming up balsa cores when mounting deck hardware, but for plywood? Does anyone have pictures showing how they've done the epoxy thing, or even pictures of an oversized hole that's been filled? I can't ever remember seeing the oversized hole/epoxy method on any OEM deck hardware -- is it only necessary on older boats?

My experience has been just the opposite regarding 'old' work. The old epoxy gets brittle and after I break a screw loose, I can back it out by hand, but the old 5200 makes it necessary to use the driver to get the fastener all the way out. I feel much more comfortable with 5200 for sealing fastener holes, although I can't speak to using it for structural bonding (like hull to deck)...

And I agree, there's nothing that sticks well to plastic or starboard, that's why I suggested wood if the transducer mounting plate was to be 'glued' to the transom; I have experimented with something that seems to bond straboard to gel coat, but haven't tested it underwater yet...

 

[Pursuit2150]

Re: drilling holes in my boat

When I mounted a Transducer 6 yrs. ago .
I drilled small holes, using the mounting plate as a template.
Used self tapping SS screws , applied Marine-tex in the area, mounted the Transducer. & never had a problem

 

[dingbat]

Re: drilling holes in my boat

When you're using the oversize hole/epoxy method, how do you keep the epoxy in the (horizontal or blind) hole, and how do you know if it's all the way to the bottom of the blind hole. Also, I assume the epoxy method sould be used on the mounting bolts for the outboard or outdrive, but I can't remember ever seeing it used there...most are sealed w/ silicone or 5200. I can certainly see using the epoxy method for firming up balsa cores when mounting deck hardware, but for plywood? Does anyone have pictures showing how they've done the epoxy thing, or even pictures of an oversized hole that's been filled? I can't ever remember seeing the oversized hole/epoxy method on any OEM deck hardware -- is it only necessary on older boats?

My experience has been just the opposite regarding 'old' work. The old epoxy gets brittle and after I break a screw loose, I can back it out by hand, but the old 5200 makes it necessary to use the driver to get the fastener all the way out. I feel much more comfortable with 5200 for sealing fastener holes, although I can't speak to using it for structural bonding (like hull to deck)...

And I agree, there's nothing that sticks well to plastic or starboard, that's why I suggested wood if the transducer mounting plate was to be 'glued' to the transom; I have experimented with something that seems to bond straboard to gel coat, but haven't tested it underwater yet...

I?ve seen enough rotten transoms not to spend the time to do things right.

Here are instructions for using this method.
http://www.westsystem.com/ewmag/21/practical.html

As for the wood mounting plate, it rots and it looks bad. Might as well do it right the first time around.