AluminumAlloyBoats.com

Hi Folks,

Does anyone know how these "bumpers" are attached and where I can get replacements.

I don't want to bug Pacific, if I don't have to, for such a small item.


Cheers

Rick

rubber push in bump stops....

https://www.mcmaster.com/rubber-push-in-bumpers

This is one supplier that carries ahole-lotta-stuff https://www.mcmaster.com/

Play around with key words in it's search feature and see what it comes up with.
I have noticed a bit on pricey side but many times Mc master is the place to go.

Also try MSC https://www.mscdirect.com/ for odds and ends

Just call Julie. She has never appeared to be bugged when I have called.

Be careful about attaching rubber directly to bare aluminum. I had to repair this area on my boat where a rubber bumper rail was attached all the way around the perimeter of my boat. The rubber trapped moisture against the aluminum and corroded the marerial underneath over time.

Julie at Pacific is way cool, just give her a call.

Rick,

please post or PM me your findings, I have a need for the same.

Thanks,
Ling

Tfitz, I've seen corrosion sites like this not only on your hull but on two i've been involved with since they were built- I helped build one, and modify the other over several years.

Bolts
Lots of people think a SS bolt -even 316L is inert to aluminum and that isn't true. The two metals will still react- so bolt or tapped openings will corrode - passivization and thread sealants can help reduce the reaction but drying out the connect is about all that can be done to really stop galvanic corrosion as SS to aluminum generate.

Rubber
There are whole series of rubber products with 'free carbon' or a highly reactive portion of the composition of the rubber that will interact with water (salt water) to allow carbon (a elemental form of metal with galvanic potential to aluminum) and aluminum to act as a battery- pitting or eating holes in the aluminum.

Crevice or poultice corrosion
As we've seen so many times before- if aluminum- uncoated or unprotected is wetted with a thin film of water- not free flowing or exchanged volumes like salt water rinses the deck in the open air; but where the water stands and stays in a layer between aluminum and either plastics other metals: the water looses initially looses its molecules of oxygen to the aluminum oxide. This protective film over the parent metal actually leaves a slight shift in ph of the water film.

Once the shift if great enough the water becomes acidic and that compound is able to 'take back' the oxygen from the oxide film and the underlying aluminum is the chemically corroded - attacked- converted to non-aluminum alloys and that we see when the area is opened and rinsed or brushed as pits.

So all three potential corrosion sources may be involved as causes in your picture? Cure is to use truly hot dipped galv. bolts and nuts- then to sleeve the bolts with plastic tubing kits and washers. Bedding in sealant would help stop any water catalyzed reactions.

Another step is to put a full epoxy paint system on the areas were bumpers will be bolted/screwed to the boat. Thus some super heavy layer of inert material would seal the underlying parent metal from interaction or attack by acidic compounds or galvanic interactions.

And finally; grooving the entire surface vertically so that any water can't become a trapped film- very narrow and shallow grooves could allow the surface to drain regularly - rinsing out the trapped water.

I had to weld up - grind out and finally in many locations replace the entire gunwale support from the damage that trapped water corroded into the identical area of a boat I've worked on for years doing modifications. I decided to go back with a 1/2 pipe welded top and bottom to entire gunwale -rather than to fight with the potential corrosion issue in the future.

Thanks for posting the pic- I think I recall another boat - a work boat in CA (?) that was on here in a thread about gunwale corrosion? Its good to recall these potential problems and allow others to make sure they're looking at alternatives or thoroughly well designed installations of rubber bumpers mounted directly to their hulls.

Cheers,
Kevin Morin
Kenai, AK

I repaired my corrosion by spanning the problem area with a piece of half pipe and got rid of the rubber. After welding the half pipe in place it bypassed the corrosion problem and looked way more solid. Avoid rubber on aluminum installations.

Tfitz Nice solution I'm sure it looks great.


I emailed Julie and she said that they don't use this type any more. but McMaster has them https://www.mcmaster.com/9377k53

They just screw in. But I'm concerned about corrosion being steel. I'm thinking that a nylon washer and lots of tef gel might be ok?

I'll be at my boat tomorrow and I'll unscrew the existing one to see how pacific installed them.

Cheers!

As an OEM we've used Tessilmare, its reasonably priced and easy to install.
Regards the fastening issues with galvanic corrosion, its worth tapping the hull sides so you can thread in an aluminum fastener to avoid dis-similar metals. Another way you can reduce corrosion, is paint a strip exactly the thickness of the rubber using Raptor Liner or Herculiner or SharkHyde to preserve the metal behind the rubber in case salt accumulates.

https://rubrails-tessilmare.com/?gclid= ... lcQAvD_BwE

Rick,

were you able to see how the existing ones are attached and are the same as the McMaster Carr ones ?

Thanks,
Ling

Sorry for the Late response. Yes they are the same ones as McMaster. It looks like Pacific used some silicone between the hull and the bumper, Lots of tef-gel, a threaded hole and a nylock nut backer. They are definitely NOT stainless.

I might just use a plastic washer/spacer when I replace them. I will post pictures when I get to my office.


Cheers!

Rick

Thanks for the info, Rick.

Ordered same from McMaster, along with some plastic washers. We'll see how long they last...

Pacific Rubber & Supply offers a full range of recycled products and sheet ... wheel chocks, mini satellite dish mounting pads, stall mats, rubber roll including the boat bumpers https://www.kemimoto.com/products/boat-bumpers-fenders from the Kemimoto.