Using Aluminium section

[MHS]

I’m looking to increase the amount of storage in our bow cockpit by putting in bigger lockers. I had been thinking of using aluminium angle sections to create the frame with buffalo board top and sides. 

 

Am I correct in thinking that there can be an issue of electrolysis or a similar reaction with the hull? Would I need to use an adhesive neoprene strip to keep the aluminium away from the steel?

[Tony Brooks]

Yes - if they get wet but it should be the aluminium that gets eaten away.

[Bee]

Probably a good idea to use neoprene. If you look at al bodied vehicles the al often gets all horrible and moth eaten. I expect it needs to be damp though to suffer.

Crossed with Tony's post

Edited December 5, 2018 by Bee
crossed with post

[Ian F B]

One of the problems with Ali section is getting flush joints,if you are building a box type construction.A good thick cost of paint shou!d prevent any problems with interaction.My Ali frame for my solar panel has been on for years with no problems.?

 

[Rebotco]

I've never encountered any problem with Aluminium against steel.

But Aluminium against copper is definitely reactive, with electrolysis unavoidable in the presence of moisture.

[Boater Sam]

Use ally and copper sections mixed, the resulting PD will charge your battery

[MHS]

Thanks for your comments. I will measure up and work out what I’m doing. 

[Jen-in-Wellies]

I have had stainless steel nuts/bolts/washers through aluminium section on various solar bits of my boat exposed outside for years with no obvious corrosion to either.

 

Jen

[MHS]

39 minutes ago, Jen-in-Wellies said:

I have had stainless steel nuts/bolts/washers through aluminium section on various solar bits of my boat exposed outside for years with no obvious corrosion to either.

 

Jen

I would want to use stainless sections as first choice except for the cost. I would definitely use stainless bolts as you suggest. I never use non-stainless fittings on the boat as you just store up problems for later. 

[blackrose]

I think there's a bit of a misunderstanding about dissimilar metals in contact and electrolysis. It can only happen in the presence of an electrolyte. That means it must be immersed or in standing water. If it just gets wet any action would stop as soon as it dries out. How many boats have aluminium windows bedded in with only a bead of sealant? 

 

That is all you need. 

 

I have aluminium cleats and an aluminium generator locker - no problems whatsoever after many years. I think we often forget that our boats have different metals all over them, from stainless screws to brass mushroom vents. 

 

 

Edited December 7, 2018 by blackrose

[BWM]

21 hours ago, blackrose said:

I think there's a bit of a misunderstanding about dissimilar metals in contact and electrolysis. It can only happen in the presence of an electrolyte. That means it must be immersed or in standing water. If it just gets wet any action would stop as soon as it dries out. How many boats have aluminium windows bedded in with only a bead of sealant? 

 

That is all you need. 

 

I have aluminium cleats and an aluminium generator locker - no problems whatsoever after many years. I think we often forget that our boats have different metals all over them, from stainless screws to brass mushroom vents. 

 

 

Most aluminium used for the purposes you mentioned are anodized, and similar to most metals, different alloys have varying resistance to corrosion. 

[MHS]

Just about finished my bow locker project. It has massively increased the amount of storage and created a better seating arrangement. 

The weather has held me back a bit. I have used rubber (horse) matting on the floor. I just need to sand down the floor now and give it a few coats of paint 

[blackrose]

On 08/12/2018 at 15:53, BWM said:

Most aluminium used for the purposes you mentioned are anodized, and similar to most metals, different alloys have varying resistance to corrosion. 

 

If anodising the surface of aluminium increases its overall nobility then it's unlikely it would end up exactly the same nobility as that of mild steel? Different alloys do have varying resistance to corrosion, but in contact with dissimilar metals one will still be anodic and the other cathodic - but only in the presence of an electrolyte. That was my point.

 

Anyway, my non-anodised aluminium generator locker is showing no signs of galvanic corrosion or pitting after 6 years.

9 hours ago, MHS said:

Just about finished my bow locker project. It has massively increased the amount of storage and created a better seating arrangement. 

The weather has held me back a bit. I have used rubber (horse) matting on the floor. I just need to sand down the floor now and give it a few coats of paint 

 

You've done a top job there.

[Murflynn]

hope the BSS man doesn't say you've obstructed the ventilation.

[WotEver]

2 hours ago, Murflynn said:

hope the BSS man doesn't say you've obstructed the ventilation.

Good point. Perhaps the starboard upright panel should have vents fitted. 

[Graham Davis]

If you are going to use that for a seating area, you will need some good cushions, as ali chequer plate is uncomfortable and cold. And those cushions will need to be secured to the surface otherwise I can see them falling off. Otherwise it looks an excellent job.

[MHS]

4 hours ago, Murflynn said:

hope the BSS man doesn't say you've obstructed the ventilation.

I haven’t forgotten that. I have the new vent which I will fit in the front door. The vent in the scuppers was so low down that on washing the bow I once managed to get water into the cabin.

2 hours ago, Graham Davis said:

If you are going to use that for a seating area, you will need some good cushions, as ali chequer plate is uncomfortable and cold. And those cushions will need to be secured to the surface otherwise I can see them falling off. Otherwise it looks an excellent job.

We will be looking at getting some waterproof cushions made. I have formers in mdf for the shapes and thought we might use pop studs to secure them. 

Edited June 25, 2019 by MHS

[blackrose]

On 25/06/2019 at 10:52, WotEver said:

Good point. Perhaps the starboard upright panel should have vents fitted. 

 

Why not just cut a couple of 3" dia holes in the bow doors and fit some anodised aluminium louvres on top?

Edited June 30, 2019 by blackrose

[blackrose]

On 24/06/2019 at 18:17, MHS said:

Just about finished my bow locker project. It has massively increased the amount of storage and created a better seating arrangement. 

The weather has held me back a bit. I have used rubber (horse) matting on the floor. I just need to sand down the floor now and give it a few coats of paint 

 

 

Can you explain how you've attached the load bearing aluminium angle frame to the bulkheads please? I wouldn't mind doing something similar. Also are the lids hinged or do they just lift off?

On 25/06/2019 at 13:05, MHS said:

I haven’t forgotten that. I have the new vent which I will fit in the front door. 

 

Ok, you've already decided to do that.

[MHS]

1 hour ago, blackrose said:

 

Can you explain how you've attached the load bearing aluminium angle frame to the bulkheads please? I wouldn't mind doing something similar. Also are the lids hinged or do they just lift off?

 

Ok, you've already decided to do that.

The aluminium angle is fitted to the bulkheads with stainless steel brackets. These are again protected with neoprene strips to prevent any reaction. 

 

The lids simply lift off. I did think about having one massive lid which would be hinged at the front. 12v Linear actuators could then be used to lift it. Decided it was simpler, cheaper and more reliable to go with 3 separate lids. 

[blackrose]

I was thinking of building 2 benches using aluminium angle but was reluctant to drill and put any brackets onto the gas locker bulkhead in case that constituted a BSS fail. There was a thread on this and the rules are a bit ambiguous but I decided I'd have to support the aluminium angle another way at the front.

[MHS]

I couldn’t see anything in BSS Examination Checking Procedures – Part 7 Liquefied Petroleum Gas (LPG) systems that would stop you from doing it.

The fittings on my lockers are well above the top and valves of the gas bottles in the locker. 

Edited June 30, 2019 by MHS

[WotEver]

12 minutes ago, MHS said:

I couldn’t see anything in BSS Examination Checking Procedures – Part 7 Liquefied Petroleum Gas (LPG) systems that would stop you from doing it.

The fittings on my lockers are well above the top and valves of the gas bottles in the locker. 

It’s the bit about holes in the locker. I can’t be bothered to find it right now but iirc in the other thread we concluded that if any penetrating bolts were well sealed with goop and had their nuts on tight then it would probably be acceptable. 

[blackrose]

33 minutes ago, MHS said:

I couldn’t see anything in BSS Examination Checking Procedures – Part 7 Liquefied Petroleum Gas (LPG) systems that would stop you from doing it.

The fittings on my lockers are well above the top and valves of the gas bottles in the locker. 

 

If your holes were above the height of the gas bottles that's fine. I was looking to build benches half the height of the well deck to gunwale so my bolts wouldn't have been higher 

18 minutes ago, WotEver said:

It’s the bit about holes in the locker. I can’t be bothered to find it right now but iirc in the other thread we concluded that if any penetrating bolts were well sealed with goop and had their nuts on tight then it would probably be acceptable. 

 

IIRC that was the conclusion of one or two contributors, but others disagreed. 

 

Edit: No, you're right. I found the thread and Rob from the BSS said it should be ok.

Edited June 30, 2019 by blackrose

[MHS]

9 minutes ago, WotEver said:

It’s the bit about holes in the locker. I can’t be bothered to find it right now but iirc in the other thread we concluded that if any penetrating bolts were well sealed with goop and had their nuts on tight then it would probably be acceptable. 

I’ve had a really good look and can’t see anything, but happy for you to correct me. 

2 minutes ago, blackrose said:

 

If your holes were above the height of the gas bottles that's fine. I was looking to build benches half the height of the well deck to gunwale so my bolts wouldn't have been higher 

Depending on the height of your cockpit deck, why not fit them at gunnel height to maximise storage and create a raised seating area?