Andrew Nisbet

Hi John , I have heard really good things about Arbomast br which is a butyl sealant, it doesn’t have any adhesive properties but by the sounds of it and the feedback I have heard from others it will seal fittings and windows etc for decades without problems. And if you do ever need to re-apply it’s easy to remove and start again.

Hi Alex thanks for your question – if we are talking about a table top that has recently been oiled I would personally lightly sand the area that you want to adhere with some 220 grit. Most adeshive sealants will struggle to stick to an oiled surface. Contradictory to this I recently used an old oak table that had been waxed for a worktop. I had to seal and mount a stainless steel sink with bathroom sealant. I forgot about the wax but despite of that it’s still holding strong. Long story short; most things will work it just depends how long you want them to last. Aslong it doesnt compromise safety or structure what have you got to loose. Hope that helps.

Hello Lee- thanks for getting in touch are you able to explain a little more. When you say you’re resealing – are you trying to bond glass directly to fibreglass with no other mechanical fixtured aka screws or bolts?

Hello Steve – Most Butyl sealants don’t offer any adehsive properties especially Arbomast BR. Arbomast would work fine if you are using other mechanical fittings such as screws, bolts or rivets. With Butyl sealants you are essentially creating a non-setting gasket. If you want to bond the perspex to the fibreglass you must use an adehsive sealant that doesn’t affect or damage perspex. If you look at the datasheet for most adehsive sealants they will provide you with a list of suitable applications.

Hey Derek, it is indeed. I’m dropping some new content this week on dual engine exhaust monitoring- be sure to check it out.

Hey John,
I don’t think I’m fully understanding what it is you need to repair. Surely where the rudder exits the hull there is some kind of shaft and gland?
Would this not normally packed with saltwater grease?

Can you email me over some photos?
Kind Regards

Hey Peter,
Sorry for the delayed response.
I’m trying to visualise what it is you’re trying to achieve, I agree that a few photos could definitely help, send them over to [email protected].

You have mentioned screw tab fasteners and silicone, which suggests to me that you are not relying on the mechanical adhesion that those two 3m sealants provide. It is generally said that you would never use any of those products on something that has to be taken apart. Even if your end goal is bedding that lasts forever, like all things in the marine environment it will need to be maintained. Therefore a product with less mechanical bond would be suitable. However, you mention the bond to glass, any good outdoor window sealant should suffice but personally, I’d stick with Sikaflex EBT, or CT1. May I suggest you run a few tests with some glass and find a product you’re happy with? If not I have some CT1 I can run a test with on your behalf.

You’re going about finding a solution the correct way, the datasheet is key. Elongation, breaking points, flex, UV resistance. Let’s find you a solution.

Hey John, Would it be possible to send me some more photos – [email protected]

That’s a good question If you’ve still not found your sealant. I could run some tests on your behalf, how long have you got until you need to complete the work? The datasheets should list all suitable materials but granted in most cases, it’s going to just state “metal”.
If you’ve not found a solution, I’ll have a play, I have some 316 In my workshop. Kind Regards

Hey Paul,

My first thought , what’s caused the corrosion in the first place, do the anodes need replacing and are there earthing issues with the leg.

I’m trying to visualise the issue, the swaging makes it a little more difficult. I’m not entirely, sure how any tube simply put through and hole will have a good seal. For a gasket to work you really need tension pushing outwards from the ID to seal. rubber changes over time, due to the elements and exposure.
Do you have water ingress? through the shield and into the hull?
If it was me i’d probably get a coded welder patch the hole and have a designated skin fitting with shutoff valve for the inlet.
However, your proposed method could work
ultimately you’ve got to look at what you need to achieve and then check the datasheets.
If you’re bonding rubber to a painted surface then I’d personally i’d use emery paper to remove the paint then your bonding, rubber to aluminium only.
Or you could simply key the surface of the ID.
You need good mechanical adehsion with flex. Look at the datasheet for Sikaflex 291i. You don’t want to use the 3M products as the hose at some point will need replacing.
Let me know what you go with- good luck.

Hi I’ve read your article several times and really appreciate the information, we have a fibreglass boat with windows in aluminium frames, we have leaks in several places, so im hoping to be able to dig out the old sealant and re seal the windows. We also have a number of small leaks in the roof (fibre glass) which we need to fill as well as re sealing some of the external fixtures ie hand rails. What sealant would you suggest for the windows? Aluminium to fibreglass? Also could we use the same sealant for resealing the holes made by fixtures? Thanks so much for your help. Regards Sarah

Thank you! We’ve just bought a river cruiser with lots of flaking paint, it seems the previous owner did a botch job painting over dirt and grime 🤦🏻‍♀️ I’m just in the process of scraping off the excess loose paint before using the chemicals 🤞🤞🤞