Transom LEDs install

[552Evo]

What’s people’s thoughts in regards to drilling through the transom to run the supply cable for underwater transom LEDs ? I’m guessing it’s always better to not have unnecessary holes under the water line.

My boats fibreglass.

This being the case I’ll go through the transom above the waterline and plug it up with the appropriate sealer, then make it look pretty with one of those stainless cable hood things ( I don’t know their proper name )

Any mounting screws for the LED fixture and cable clips will still need to be sealed up too.

Is this the best way ?
I don’t want to end up with a soggy transom.

Or are my concerns out of date ? Should holes through the transom under the waterline be good with the modern 3M and Sika goop.


Saltwater fishing, boat mad but has a job that gets in the way.

[gazza2006au]

What i would do is find a good marine grade double sided tape for the light and run the cable up over the transom neatly than thru the steering cable hole this way u drill zero holes

[552Evo]

Thanks gazza ive never thought of double sided tape ?
Is it really that good ?

The steering lines and all the engine cables are in a sealed flexible conduit from the transom pod to the lower engine cowl so I don’t think I’d want to break into that.


Saltwater fishing, boat mad but has a job that gets in the way.

[scottar]

Got trim tabs.If so get some brackets fabbed up and mount them on the tabs. Can even change the angle a bit then

[552Evo]

Thanks scottar but no tabs.


Saltwater fishing, boat mad but has a job that gets in the way.

[gazza2006au]

Even if u put a 4mm hole thru the splash well your not doing any damage i would most definatly avoid the transom hole as u mentioned

Art and craft thin 9-10mm double sided tape is so bloody strong what ever u stick together breaks before the tape gives way so there are super strong tapes out there

[ericcs]

Can you not use the same hole for the transducer on one side, then replicate that on the other. if you have one hole through the transom, surely one more won't be a problem if it's sealed the same way!

[scottar]

So get tabs.......problem solved;)

[Noelm]

Don't know of any tape that will last long term under water and out in the weather, might be a silicon that might maybe.

[552Evo]

Can you not use the same hole for the transducer on one side, then replicate that on the other. if you have one hole through the transom, surely one more won't be a problem if it's sealed the same way!

Thanks ericcs, I’ve already added a second transducer cable to the existing transom hole on the starboard side and I definitely remember it being a tight squeeze that time so I don’t think another cable will fit,,,
Unless I can get a larger cable hood ( ??? Name of stainless cable protector thingy ???)
I’ll have a go at it, bugger of a job trying to expand an existing hole, but you get that on these jobs ha ha.
See you’ve talked me into it now.
I’ll thank you after the job is complete and I’ve lost skin trying to expand the existing hole ha ha.


Saltwater fishing, boat mad but has a job that gets in the way.

[stevej]

don't just drill a hole and seal it with sika etc
drill the hole a bit bigger and epoxy seal the inside surfaces of the hole so the epoxy soaks in to what ever ply that's in there

use a mix of epoxy and talc or microbeads

then put the wire through and use a sealant

[gazza2006au]

You can buy drill bits that drill sideways mate they are specifically designed for enlarging holes they work on a sawing action the side of the drill bit is like serrated up its shaft

IMO screws on transoms were a 1970-1980's fix for the old timers these days we have a wide variety of options to chose from for fixing stuff to transom's that don't require screws

Today we live in a high tech world and everything is at our finger tips, that light your putting on the transom has no force on it so basically anything will hold it on so long as u do a really good prep job

[stevej]

it will have suction applied to it from the water travelling under the boat an dup at speed this can be quite significant

best way is to glass a block to the transom and screw into that for any transom fixings

[inveratta]

don't just drill a hole and seal it with sika etc
drill the hole a bit bigger and epoxy seal the inside surfaces of the hole so the epoxy soaks in to what ever ply that's in there

use a mix of epoxy and talc or microbeads

then put the wire through and use a sealant

yes....most boatbuilders dont do this but....its the most effective way to seal a hole.Sika breaks down and fails over time....but its quick cheap and quite good.If you want to mount something below the waterline...drill an oversize hole back it with tape fill with epoxy let set and then drill a screw hole as required into the epoxy and epoxy or sika if you must the screw.. and sika the transom mating surface there simply should be no pathway for water to enter via the interface between the screw and the epoxy and pass into the transom.If later you want to release the screw just heat it up with a heat gun and that should be enough to soften the epoxy to allow you to unscrew.

[brett62]

yes....most boatbuilders dont do this but....its the most effective way to seal a hole.Sika breaks down and fails over time....but its quick cheap and quite good.If you want to mount something below the waterline...drill an oversize hole back it with tape fill with epoxy let set and then drill a screw hole as required into the epoxy and epoxy or sika if you must the screw.. and sika the transom mating surface there simply should be no pathway for water to enter via the interface between the screw and the epoxy and pass into the transom.If later you want to release the screw just heat it up with a heat gun and that should be enough to soften the epoxy to allow you to unscrew.

Yep this is what I did once I repaired the stern on my boat. 552Evo just make sure you use epoxy as inveratta has said. If you use polyester it will shrink and is not as good at penetrating the timber and will allow water through. When I did the holes for the bungs I hole sawed about 10mm bigger in dia and the holes for the screws I also drilled out over size and filled. Takes a little longer but about the best way to stop the water getting into the timber.

stevej has a good idea also with glassing in blocks for transom fittings. I am in the process of doing this for transducers at present so don't have to worry about water as spent many hours repairing the transom from screw holes done wrong.

[552Evo]

You can buy drill bits that drill sideways mate they are specifically designed for enlarging holes they work on a sawing action the side of the drill bit is like serrated up its shaft

IMO screws on transoms were a 1970-1980's fix for the old timers these days we have a wide variety of options to chose from for fixing stuff to transom's that don't require screws

Today we live in a high tech world and everything is at our finger tips, that light your putting on the transom has no force on it so basically anything will hold it on so long as u do a really good prep job

Thanks gazza, re prepping the surface: so I went to the local big hardware joint today for a quick look I was thinking prepsol coz I need to touch up the skeg on the outboard ( sandy bottom got me in a channel) but they don’t sell it,, I ended up getting a small spray bottle of isopropyl alcohol, would this sort of stuff damage gellcoat if I was to prep the surface to try and stick on these LEDs?

Thanks Inveratta and stevej,
I’ll have to get me one of them drill bits, sounds good.
I knew boat builders used the “oversized hole filled with epoxy” method for outboard motor mounting holes in the transom, but is that method really used to mount all this accessory sort of stuff too ?
Don’t get me wrong, I can see it’s the best method for sealing holes through the transom and I honestly do thank you for your opinions but is that how I should be preparing all holes in the transom even above the waterline - I’m thinking not only the cable holes through the transom but mounting holes for trim tabs and transducers and “LEDs” and whatever else others have under the waterline.
I hope I’m not coming across the wrong way, I’m very much a novice at the marine/boatbuilding thing and happy to admit it, I just want to understand.
If that’s the consensus I’ll have to draw out the 2 transducer cables from the console and under the floor to get them back out of the existing hole. Then open up the hole and do the epoxy backfill. Then mount up the LEDs and run the cables.



Saltwater fishing, boat mad but has a job that gets in the way.

[stevej]

some fiberglass places have offcuts of 50mm thick castings to use which work well
can also coat the screw in Vaseline while the epoxy Is wet and comes out easy ones its set

[Fed]

I'd hang the lights over the back of the boat & roll them up when I was finished.
Are they for attracting bait or to look pretty?

[gazza2006au]

I'm not to sure on how to clean it maybe the alcohol wipe or some acetone but don't hold me to it i don't know if it will remove the paint, its like anything your sticking on prep the surface and it will get a good bond even if u have to replace the tape in 6 months it wil only take a couple minutes where as if u drill holes in the transom u could be spending weeks replacing the transom

[552Evo]

I'd hang the lights over the back of the boat & roll them up when I was finished.
Are they for attracting bait or to look pretty?

Hi Fed, both !


Saltwater fishing, boat mad but has a job that gets in the way.

[Homer_Jay]

Noosacat put mine on a stainless bracket off the outboard bolts.
They strongly advised against drilling holes in the transom.

[552Evo]

Sounds like I might try this double sided tape idea for below the waterline.
If that fails then I’ll try just glueing them with 3M or sika.
If that fails,,, I’ll cut the bloody things off.
Not worth risking thousands worth of boat/transom for any lights.



Saltwater fishing, boat mad but has a job that gets in the way.

[ericcs]

you could use that white cable duct with the clip on cover. smallest iv'e seen is about 16mm aquare. and you can get it pre taped!

https://www.clipsal.com/Trade/Products/ProductDetail?CatNo=900/16/16PT&c=1&ms=5&mg=320

[gazza2006au]

The other guys have offered good advice on drilling the holes im not an expert however i have bought two boats in my boating history not knowing about wet transoms one of the sellers mentioned it and i dismissed it the other seller was a retired laywer who said he didnt want me coming back complaing about problems with the boat at a later date i was only young at the time around 20 and boat purchase was 3k which was a lot of money back than, i ended up selling the boat for $1200 was a great loss

All it takes is a few tiny holes than when the boat is in the water there is pressure on those screw holes and they leak

Look at my boat the one im rebuilding there were some where around 70 holes in the transom the entire wood in the boat was rotted no doubt from holes in the transom

[552Evo]

Thanks gazza that’s all I need to hear


Saltwater fishing, boat mad but has a job that gets in the way.

[scottar]

There's typically a lot more to a rotten transom than a few properly fitted accessories. The old mans rig is older than me - all original and still solid as a rock. I turn 45 this year. Personally I use a countersink bit to clear the gelcoat - eliminates cracking and gives the sika a void to form a seal. If you want to go one step further without going too extreme, a syringe with some everdure is a good compromise.

[552Evo]

Thanks scottar, everdure ? I’ll look that up thanks.

Edit: oh so it’s a clear 2 pack sealer.
Ok I’ll keep that one up my sleeve, thanks.


Saltwater fishing, boat mad but has a job that gets in the way.

[Bremic]

I saw these suction cap led's recently

http://www.downriggershop.com.au/outdoor-lighting.html

I thought they would be a good option if you don't use them very often. Stick on and off as required.

He has another option on there that you could suspend under a float.

[Triple]

No drilling/doublesided taping required..
https://www.whitworths.com.au/led-bung-light-with-base-white

[552Evo]

So I opened the packs of lights today ( all prepared to give the double sided tape method a go).
I found where the sealed cables come straight out of the fitting that if I used double sided tape that the cable bend (where it comes out of the fitting) would put too much pressure on the , even with 10mm thick rubber gasket. I didn't think the tape would last so I bit the bullet, countersunk holes, lots of 3m sealant and screwed the 2 lights in place.
I'll wire them up tomorrow.
Unfortunately I have to attend my paid career shortly, so I'll run the cables and wire them up tomorrow.


Sent from my iPad using Tapatalk

[stevej]

There's typically a lot more to a rotten transom than a few properly fitted accessories. The old mans rig is older than me - all original and still solid as a rock. I turn 45 this year. Personally I use a countersink bit to clear the gelcoat - eliminates cracking and gives the sika a void to form a seal. If you want to go one step further without going too extreme, a syringe with some everdure is a good compromise.

ill disagree only takes one 6mm screw with no or poor sealant to stuff a plywood transom, although most transoms fail through that shitty ally capping strip
this is what my cruisecraft had from the factory
2 transducers
4 engine bolts
a ladder
a burley bucket
2 live bait tank inlets.
and two ski hook things

[gazza2006au]

Some would be amazed how a tiny 4-6mm hole lets in so much water on a transom if u go put a hole in a bucket than fill the bath tub hold the bucket 1 foot under water as in a boat transom and you'll see actually how much pressure there really is the water flow might not sink a boat in 1 hour but the water pressure behind it is huge

[Chimo]

2,31 ft head = 1 psi

[ranmar850]

No drilling/doublesided taping required..
https://www.whitworths.com.au/led-bung-light-with-base-white

I have one of these at home. I was hoping it would fit the 32mm bung i had fitted to the new boat, but it's some weird thread, so I would have to change the bung base as well.

[ranmar850]

A boatbuilder whom I respect greatly--started on wood, moved to fibreglass, recommends the use of 24 hour araldite if you need to penetrate or plug a wood-cored glass transom. For large thru-holes such as outboard mounting bolts, you have some choices. You can drill the holes slightly oversize, then coat the inner surfaces of the holes with the araldite. Force it into the laminate--if the hole is big enough, use your finger, if not, cut down a strong stick and really work it in. Leave overnight to cure, then sika the bolts when you fit them. For screwing in self-tappers, screw them in to make the thread, then remove, fill the hole with araldite, then screw back in--this is called wetbonding. if you want to be able to remove them later, put some form of release agent on the thread--some CRC, or anti-seize smeared on very thinly. Don't use screws any longer than necessary. You can also drill a hole well oversize, fill with bog, allow to set, then drill the screws into that. You can also wetbond with thru-bolts and hull fittings, but you will need some heat applied later( hot air gun is enough) to undo them. As for plugging existing redundant holes, drill them out to clean wood, drive in a hardwood dowel coated with the same araldite.

iIcame across a method of actually getting Starboard to bond to gelcoat on THT a while back. It involves "flame treating" the bonding surface first--this makes the previously "stick to nothing" starboard receptive to sikaflex-type bonds. Would be just the shot if you wanted to mount a piece on the transom to screw stuff to. I'll try and dig up the link,very interesting.

How about just making a bracket on top of trim-tabs to mount them?

[552Evo]

Thanks ranmar great info about araldyte. I. know an old chippy he prefers the stuff on specific joins coz it soaks better into the surrounding wood, as opposed to the construction adhesive.
My boat doesn’t have tabs, I wouldn’t know if it even needs them, so I guess not [emoji4].
When drilling today in the outer side of the transom (closest to the gunwale) I never even struck wood, just a thick fibreglass outer ?
I think it’s the way my boat is constructed- I was looking at build photos just now of when the upper and lower hull were prepped for joining.
The motor is on a pod - which has marine ply within the supporting face.
It looks like the recessed part of the transom proper has a timber brace panel extending the full width/beam of the transom.
So anyway I’m pretty sure I got plenty of sealant in the holes, so it won’t leak and the light fitting is pretty small and all squeezed in by the 10mm rubber gasket held down by 4 screws.
IF water does seep past the screw and glued rubber seal it won’t be soaked up by wood.
IF enough water does deep past the screwed, glued holes it should be pumped out the bilge.
IF this happens I’ll follow it up then and ditch the lights and glass up any holes. [emoji4]


Saltwater fishing, boat mad but has a job that gets in the way.

[ranmar850]

OK, some links. First one looked good, but failed after 12 months https://www.thehulltruth.com/boating-forum/760463-successfully-glued-starboard.html

This one looked a little better https://www.thehulltruth.com/marine-electronics-forum/275156-glueing-king-starboard-2.html

And another https://www.thehulltruth.com/boating-forum/724873-adhesive-starboard.html

[gazza2006au]

Chimo since we are quit regular to psi we often under look even 1psi because our tyres are 30-45psi so we often think 1psi is absolutely nothing but it is pressure than when u factor in voids in plywood (only a percentage of us use marine grade) there is a open channel for the water to seep in and channel along

From what i have head a good source for a soggy transom is the caps of the transom (upper left and right top) which dont get laminated and everytime it rains water seeps into the ply transom

What the BMD guys were doing is drilling the outboard mounting holes larger and inserting and gluing into place pvc tubes than painting