Options on non skid

[Jim Jones]

Originally Posted by poiu

My first thought is being in a bandit infested area is tragic and eclipses any heat problems. Good luck to you, but I wouldn’t be there.

As to your heat issue, the best cure as with so many things is to remove the cause of the problem, rather than the symptoms. The cause being the deck getting hot. The cure is heat reflective paint. Pure whites reflect nearly all the heat, off whites absorb a lot of heat, far more than I expected and any other colour absorbs between half and most of it. Your grey will be in the middle to upper end I expect. If you are stuck on Jotun, ask for their IR absorption data for their various white (and colour) shades or get samples and test yourself with a thermometer.

Glare is dealt with by polarized sunglasses. A necessity anyway in a sunny place.

Your bandit visibility won’t be worsened much by the deck as little of it is likely to be seen from the sides. A 1/2” cal gun replica on the foredeck might be of use.

I have a teak deck, which needs replacing. After years of deliberating I have decided to do it in Awlgrip G8001 with the matching grit. It is their least heat absorbent paint if I recall correctly.

Agree with most of that. The bandit visibility issue is as you say not that great from water level. I suppose the real issue is the visibility of the saloon sides and awning sides (I've had a custom awning built that bolts to the deck- bolted down so I can remove it as needed). There are some issues of visibility of the deck but its so situation specific as to be unuseful to anyone here so wont discuss it further as it just clutters up the thread - more so then I already have.

I know I really need to go white - but you hit the nail on the head - " being in a bandit infested area is tragic and eclipses any heat problems". I dont know about tragic but the rest is very correct. As for the bandits, we only have to deal with them at night - the lake is alive at night with smugglers criss crossing the lake in small wooden boats/canoe style boats - bit bigger then a canoe but smaller then a bigger plank boat.

Three countries meet in the middle of the lake - so its a free for all most nights out there. I can get cheap diesel every morning near to where I live :-) as its cheaper across the border then the country I am in. So it comes in every night. There is a nice under the cover of darkness trade of sugar and cooking oil going into Congo. Then there are the bandits reliving these smugglers of thier goods. This is the problem I am facing out there at night.

So a hot deck during the day or keeping as low a profile as possible at night.

I think I am going to have to get a sample of the aerogel poly and do some test with on some scrap Aluminium since it seems no one can really say what the result will be. The aerogel is an amazing insulation material - which I could insulate the inside of the hull with aerogel blanket but I am not that crazy rich. The aerogel paint is not that crazy though so planning on painting the inside with it - International Interguard 269 epoxy primer as a first coat (sand blast the inside of the hull first) then a poly over that.

What poly to use is the crux of it - I could do an International or Jotun poly first then put a coat of the aerogel OVER the International or Jotun poly. So end up with 2 coats of poly INSIDE and then the same on the outside.

The issue I have and am concerned about is will the second coat of aerogel poly causes issues with the 1st coat of International or Jotun poly ?

Looks like testing on some scrap plate is the only way forward. I have had to do quite a bit of replating on the hull due to corrosion (water tanks were badly corroded) so we have enough scrap plate to test on.

[Uncle G]

Jim Jones said: "The aerogel paint is not that crazy though so planning on painting the inside with it - International Interguard 269 epoxy primer as a first coat (sand blast the inside of the hull first) then a poly over that."

Why are you planning on painting the inside of an aluminium deck? You can leave it bare.
50 to 75mm of insulation (glass wool, kingspan, polystyrene...) and some cheap 3 or 4mm exterior ply is all that's needed.

re the outside of the deck, Jotun do a non-slip aluminium aggregate to go in their polyurethane paint.

re your night-time problem, can you rig permanent camouflage nets between your deck and the guard rails - all round the boat? Then the deck and the coachroof won't be seen from the water.

[Jim Jones]

why paint the inside of an Aluminium boat ?

Like a steel boat an aluminium boat always corrodes from the inside. I have had to do quite a bit of replating of the hull due to corrosion on the inside. Where there was fluids in touch with the aluminium there was corrosion - in the engine bay the wet exhaust had been leaking at both the exhaust elbow and at the actual wet exhaust system itself. This caused some very bad corrosion in the engine bay floor that has been patched with new plate - a hole was blown through when we sandblasted the outside of the hull - in other area's there were pits that were 1mm of plate left in the 8mm plate used along the flat chine of the bottom of the boat.

In the galley, the sinks were leaking very badly and the bulkhead there was finished - when we took it out to dig around in there we found more corrosion pits - all along where the leaking water run back into a rear bilge. That same rear bilge also had a hole blown through when sand blasting. The shower area had a grey water tank made of aluminium that was badly corroded.

ANYWHERE there was fluids in touch with the Aluminium plate on the inside there was corrosion.

So an epoxy primer then a tough thick coat of poly over that acts as a barrier coat - if any fluid leaks again it will sit on the poly - not the Aluminium plate itself. Also the poly will act as a dielectric - if I ever do get a stray wire running along he hull again I have a barrier to stop it touching metal.

Re insulation - decided to go with Armaflex - I only have 37mm of space in the ceiling for insulation - cant afford to do any thicker as the head room will get lower and as it is i have about 40mm of head room before the ceiling liner goes back in.

Considered netting over the deck at night - bit cludgy.

[Uncle G]

In the places where you found corrosion, had it been painted previously? If the paint had been damaged, then corrosion would definitely creep along under the paint and could be quite severe.
I have built and owned several aluminium boats over 40 years and exposed 'unpainted' alloy inside the boat does not corrode to any extent - in my experience. Whether wet or dry.

I'd use 25mm Kingspan (polyurethane foam sheet) with a 3.5mm painted ply cover on the deckhead if you're limited for height.

I agree that covering the decks would be a pain, that's why I thought permanently fixing a camouflage 'fence' around the deck would be an idea.

[Jim Jones]

There was no paint where the corrosion was except the grey water setup.

It depends on what the fluid touching the plate is.

In the engine bay it was exhaust gases mixed with sea water - massively corrosive !

In the galley area it was washing up water - full of soap liquids and what have you. Also corrosive!

In the grey water tank that someone added along the way it was showering water - soap/shampoo - again corrosive.

Water tanks had massive corrosion in them! Had to rebuild the tanks - took weeks. Big big job. There were areas of corrosion on the sides of the water tanks - so I epoxied plates to the sides of the water tanks - we couldn't weld because the water tanks are next to the ballast and the plate there is thin - we tried to TIG it but it was burning holes through to the ballast so we epoxied up the hole we burnt through and epoxied plates to it. Best we could do. Was going to convert the water tanks to diesel - once diesel touches the insides of the water tanks there is no more corrosion ever. But no going back to fresh water ever again either - so big decision.

The diesel tanks inside looks like brand new plate.

All other areas no issues.

I had the Jotun rep over to take a look and make recommendations - he spotted it immediately - in the grey water tank area there was some interguard 269 left on a small length of stringer that we didnt take off - he scraped some off - the surface under it was not sand blasted - it was clean Aluminium. And the 269 was only applied in a small area - then epoxy put down over the rest of the plate - no adhesion so that soapy water over the years got under it.

To be clear - the only area that had any paint on it was the grey water tank - it was poorly painted - no prep at all!! - and we saw the results.


I know all the arguments pro and con to this. I have the interior stripped out for the plating work we had to do - so while its out I am going to put a primer and poly on it - but prep is everything here - so will sandblast the interior - hell of a messy job but now is the time. I would never do this if we only removed part of the interior - way too intrusive!

I have decided that while i am this stripped down I may as we prep her extra well and paint it with primer and poly. This gives the chance to us e that areogel poly to add some extra insulation.

[Jim Jones]

Originally Posted by Uncle G

In the places where you found corrosion, had it been painted previously? If the paint had been damaged, then corrosion would definitely creep along under the paint and could be quite severe.
I have built and owned several aluminium boats over 40 years and exposed 'unpainted' alloy inside the boat does not corrode to any extent - in my experience. Whether wet or dry.

I'd use 25mm Kingspan (polyurethane foam sheet) with a 3.5mm painted ply cover on the deckhead if you're limited for height.

I agree that covering the decks would be a pain, that's why I thought permanently fixing a camouflage 'fence' around the deck would be an idea.

I will use a thin armaflex sheet glued to the last layer of poly so that is ZERO air gap between the hull and the insulation - a similar product as Kingspan could then go in over that.

Kingspan up against the hull is not ideal as the first layer because its somewhat stiff and wont follow the curve of the hull closely enough to insure there is absolutely no air gap between the hull and insulation. I am taking no chances with insulation - this is my chance to do it right. I dont ever want to do this job again !