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Aluminium to replace wooden deck boards?


Tony1

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The engine cover boards on my cruiser stern are getting a bit rotten around the edges, particularly the smaller one over the weed hatch, and some time in the next few months I ought to replace at least the smaller one. 

 

I must apologise as I don't know what they are made from- its some kind of ply, coated in a black plasticy film. I think there is a hexagonal pattern on the film, so perhaps it's hexaboard?

 

Anyway, despite the boat having a tonneau-style cover over the stern, which the previous owner would have made use of (in between his periodic visits to cruise the boat), and despite it being about 6 years old, the smaller board is pretty far gone- or at least the outer edges are. 

Seeing how poorly it's withstood the elements,  I don't have a lot of faith in the idea of a wood-based replacement, and I'm wondering about using aluminium chequer plate instead. It'll cost, but it will be a permanent solution. 

 

So I was just wondering- has anyone had experience on a boat with metal engine covers (or spoken to people who have these)? 

Does metal have any serious disadvantages other than cost? 

I can imagine they'll transmit the engine noise more than wood, so I might need another layer of soundproofing, and I can imagine they will be pretty heavy.

The bigger cover is maybe 5ft by 3ft- so maybe I could use two separate sheets to replace that one, to make it easier to lift and manhandle? 

 

I'm tempted to try out a replacement metal plate just over the smaller weed hatch section (about 1ft  x 3ft) , but before spending any cash I'd be very grateful to know if there are any major cons that might present themselves afterwards to spoil the party. 

 

 

Edited by Tony1
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I could be entirely wrong (not unusual btw) ... but I vaguely recall there being an issue when alumininium and steel are together. I think the alumininium weakens due to some form of corrosion induced by the steel (perhaps this is galvanic - dunno). I'd think it would need to be in contact with bare steel and ali. Hopefully someone with more and better knowledge will confirm or deny.

 

I'd guess you would have to be careful where the two met to ensure no bare steel/ali.

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1 minute ago, PCSB said:

I could be entirely wrong (not unusual btw) ... but I vaguely recall there being an issue when alumininium and steel are together. I think the alumininium weakens due to some form of corrosion induced by the steel (perhaps this is galvanic - dunno). I'd think it would need to be in contact with bare steel and ali. Hopefully someone with more and better knowledge will confirm or deny.

 

I'd guess you would have to be careful where the two met to ensure no bare steel/ali.

 

Cheers, that did not occur to me at all.

I guess using steel deck plates would solve that issue, but I dont know if steel plates would be practical, with being so heavy?  

 

 

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Lots of aluminium tread plate decks out there. Corrosion or failure of the ally is not usually a problem.

 

Things to think about:

When it is up for access below it needs to stay up, not bash you on the head.  How will you keep it up?

 

Big flat sheets of metal on top of a vibrating engine will rattle on the supports.  You need some rubber between the sheet and the supports.

 

A large  flat area of the sheet will transmit noise and vibration.  Stiffen the ally sheet with some angle ally screwed on.  Add some heavy duty sound proof to the back too.

 

If you are going to do a part fit to try ally out make sure the ally is level with the remaining buffalo boards.  A back deck is no place for a trip hazard.

 

N

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9 minutes ago, PCSB said:

I could be entirely wrong (not unusual btw) ... but I vaguely recall there being an issue when alumininium and steel are together. I think the alumininium weakens due to some form of corrosion induced by the steel (perhaps this is galvanic - dunno). I'd think it would need to be in contact with bare steel and ali. Hopefully someone with more and better knowledge will confirm or deny.

 

I'd guess you would have to be careful where the two met to ensure no bare steel/ali.

Electrical contact with liquid around, like water, aluminium will corrode in preference to steel. Can be eliminated with a rubber bump stop, or some way to avoid contact once any paint has worn off.

 

The type of plywood typically used for deck boards is epoxy bonded, with a non slip surface. Trade names like Buffalo board and Hexagrip. The way to stop the rot on sawn edges is to coat these with more epoxy resin to protect them. Do a search on here.

On weight of alternatives, Aluminium will be around 2.7 times, for the same thickness (typically 19mm (3/4")) and steel will be 10 times, however, weight can be reduced with careful design, rather than straight replacement size for size. Also a risk of more vibration with aluminium, or steel. Again can be coped with using rubber isolation, but coating sawn edges of epoxy ply gives many years use. Mine is coming up to 14 years outside and only now starting to look tatty.

Jen

 

 

Edited by Jen-in-Wellies
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Oooooh! loose aluminium just waiting to be carried off. Sorry, Just a thought, there are people who would. Biggish sheets will need to be braced underneath unless they are quite thick, they will indeed rattle and all of them will resonate at exactly the speed you want to cruise at. I think what would put me off though is that I think they can be quite slippery when wet or oily. Buffalo board or something like it is not perfect but it is likely to be the best. I tried rubber mats once on a steel deck, not really very successful

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We used aluminium to replace heavy steel deck plates on our last boat it sat on the steel u channel that had supported the steel with rubber in between, we had no problems. We saved some money buy buying it from a scrap yard!  The channel was quite closely spaced. In the current boat we have a single sheet of aluminium that lifts on  struts to access the engine it is about 5' x 5' but has a lot of reinforcing underneath to keep it rigid.

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3 minutes ago, Bee said:

Oooooh! loose aluminium just waiting to be carried off. Sorry, Just a thought, there are people who would. Biggish sheets will need to be braced underneath unless they are quite thick, they will indeed rattle and all of them will resonate at exactly the speed you want to cruise at. I think what would put me off though is that I think they can be quite slippery when wet or oily. Buffalo board or something like it is not perfect but it is likely to be the best. I tried rubber mats once on a steel deck, not really very successful

doesnt resonate if placed on rubber, chequer plate is the one to get reasonably non slip, you can put those rubber door mats with drain holes on top if you prefer

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I had aluminium chequer plate on my last boat - about 5' x 2' 6". Very heavy to lift and often had to carry it off the stern and lay down on pontoon or towpath to make sure it didn't drop on me. Rattles were not a problem once I had added self adhesive neoprene strips under all the edges so that there was no direct metal to metal contact on to the steel channels.

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One other thing - hexagrip/epoxied ply will be much warmer to stand on in winter and cooler in summer. It does need the cut edges sealing well to prevent the rot getting into it. Aluminium angle around the edges will protect them from damage but needs recessing into the surface to give a level floor.

 

springy

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Thanks everyone, thats really useful info.

 

It seems metal could be an option as long as you attach rubber edging to stop rattling etc, and maybe split the large plate into 2 sections to make it easier to lift.

 

But on the other hand, it does seem the typical life of hexagrip can be 10 years or more, and perhaps in my case there has been damage to the edges that was not sealed and allowed water in so that it rotted prematurely.

 

So hexagrip or similar is not as bad as I suspected. 

 

 

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39 minutes ago, jpcdriver said:

I had aluminium chequer plate on my last boat - about 5' x 2' 6". Very heavy to lift and often had to carry it off the stern and lay down on pontoon or towpath to make sure it didn't drop on me.

And if you drop it at the wrong time you need an aluminium magnet to retrieve it!

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2 hours ago, Tony1 said:

 

The engine cover boards on my cruiser stern are getting a bit rotten around the edges, particularly the smaller one over the weed hatch, and some time in the next few months I ought to replace at least the smaller one. 

 

I must apologise as I don't know what they are made from- its some kind of ply, coated in a black plasticy film. I think there is a hexagonal pattern on the film, so perhaps it's hexaboard?

 

Anyway, despite the boat having a tonneau-style cover over the stern, which the previous owner would have made use of (in between his periodic visits to cruise the boat), and despite it being about 6 years old, the smaller board is pretty far gone- or at least the outer edges are. 

Seeing how poorly it's withstood the elements,  I don't have a lot of faith in the idea of a wood-based replacement, and I'm wondering about using aluminium chequer plate instead. It'll cost, but it will be a permanent solution. 

 

So I was just wondering- has anyone had experience on a boat with metal engine covers (or spoken to people who have these)? 

Does metal have any serious disadvantages other than cost? 

I can imagine they'll transmit the engine noise more than wood, so I might need another layer of soundproofing, and I can imagine they will be pretty heavy.

The bigger cover is maybe 5ft by 3ft- so maybe I could use two separate sheets to replace that one, to make it easier to lift and manhandle? 

 

I'm tempted to try out a replacement metal plate just over the smaller weed hatch section (about 1ft  x 3ft) , but before spending any cash I'd be very grateful to know if there are any major cons that might present themselves afterwards to spoil the party. 

 

 

Yes. I've had aluminium engine / weed hatch covers on my semi trad for 25 years without any real issues. Lighter than steel they are braced underneath but I would have wanted that with any material considering the unsupported area. Soundproofed obviously with closed cell foam strips around the edge. Absolutely no maintenance .

2 hours ago, PCSB said:

I could be entirely wrong (not unusual btw) ... but I vaguely recall there being an issue when alumininium and steel are together. I think the alumininium weakens due to some form of corrosion induced by the steel (perhaps this is galvanic - dunno). I'd think it would need to be in contact with bare steel and ali. Hopefully someone with more and better knowledge will confirm or deny.

 

I'd guess you would have to be careful where the two met to ensure no bare steel/ali.

Yes, I have foam strip around the edge to counter any vibration but not a hint corrosion or galvanic reaction. Indeed I've never even thought of it before today

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2 hours ago, springy said:

One other thing - hexagrip/epoxied ply will be much warmer to stand on in winter and cooler in summer. It does need the cut edges sealing well to prevent the rot getting into it. Aluminium angle around the edges will protect them from damage but needs recessing into the surface to give a level floor.

 

springy

 

I didn't bother recessing the 2mm thick x 20mm aluminum angle that I stuck around the edges of my new deckboards (with Stixall) 3 years ago. I haven't tripped on the edges yet. I just left a 5mm gap at the corners for drainage and made sure the edges of the ply were well sealed.

Edited by blackrose
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3 minutes ago, blackrose said:

 

I didn't bother recessing the 2mm thick x 20mm aluminum angle that I stuck around the edges of my new deckboards (with Stixall) 3 years ago. I haven't tripped on the edges yet. I just left a 5mm gap at the corners for drainage and made sure the edges of the ply were well sealed.

or put them on the underneath! better to weld them though

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I think putting the angle on top is a better idea in terms of preventing water getting to the ply. Whatever paint sealing you do on the edges generally gets worn off when the board edges rub against the deck as you're lifting them up and down, so the angle stops that happening. But you do need to make sure you cut the boards slightly smaller to accommodate the angle.

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5 minutes ago, blackrose said:

I think putting the angle on top is a better idea in terms of preventing water getting to the ply. Whatever paint sealing you do on the edges generally gets worn off when the board edges rub against the deck as you're lifting them up and down, so the angle stops that happening. But you do need to make sure you cut the boards slightly smaller to accommodate the angle.

sorry posted too quick I was thinking of reinforcement for aluminium deck plates!!!

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2 hours ago, jpcdriver said:

I had aluminium chequer plate on my last boat - about 5' x 2' 6". Very heavy to lift and often had to carry it off the stern and lay down on pontoon or towpath to make sure it didn't drop on me. Rattles were not a problem once I had added self adhesive neoprene strips under all the edges so that there was no direct metal to metal contact on to the steel channels.

 

Did you have supporting struts underneath the plate?

 

I ask because at the moment I'm leaning towards the wood option, for a few reasons:

 

1. Soundproofing

It was very simple to screw the soundproofing sheets to the underside of a wooden board, whereas with a metal plate the attaching might not be so easy- e.g. I dont want bolts sticking out through the upper surface.

 

2. Struts needed?

The wooden board hasnt needed struts, whereas some folks are saying aluminium does need struts- that means I'll have to cut the soundproofing into sections and fit it around the struts, which I think will be a pain, but it will also reduce its effectiveness

 

3. Price

Wood seems like it will be cheaper

 

4. Soundproofing again

My engine is quite agricultural and a bit noisy. I'm guessing wood dampens the sound better in general, and if I do need extra soundproofing with metal, that's an extra cost

 

It does seem like wood (with some edging on the vulnerable corners)  is the path of least complications, and lowest price....

 

 

 

Edited by Tony1
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I have ally on this boat which is hinged with locks, 30 expensive LifePo4s need looking after! Noise wise with the diesel not bad  with the electric motor still silent  they have rubber seal on the edge where it touches the steel channel so no rattling. My old boat was the same. 

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1 hour ago, peterboat said:

I have ally on this boat which is hinged with locks, 30 expensive LifePo4s need looking after! Noise wise with the diesel not bad  with the electric motor still silent  they have rubber seal on the edge where it touches the steel channel so no rattling. My old boat was the same. 

 

Even a basic lead/acid battery bank can be expensive. My 3 x Trojan 1275s cost me 600 quid so there's no way I'd just leave them under unlocked deckboards. It always amazes me how few boatbuilders & owners have bothered to secure their cruiser stern deckboards considering there's a 5 or 6 grand engine sitting underneath plus gearbox & batteries. 

 

I've met one neighbour on the Thames who had his batteries nicked, plus a guy about 23 years ago on the GU whose engine & gearbox were stolen! That taught me a lesson.

Edited by blackrose
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3 hours ago, Tony1 said:

Did you have supporting struts underneath the plate?

No my ally plate didn't have any struts for strenghening as some have mentioned. With 2 (generously proportioned) people stood on it you could tell that it flexed down in the middle (maybe a millimetre) but it never felt unsafe or caused any problem.

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1 hour ago, blackrose said:

 

Even a basic lead/acid battery bank can be expensive. My 3 x Trojan 1275s cost me 600 quid so there's no way I'd just leave them under unlocked deckboards. It always amazes me how few boatbuilders & owners have bothered to secure their cruiser stern deckboards considering there's a 5 or 6 grand engine sitting underneath plus gearbox & batteries. 

 

I've met one neighbour on the Thames who had his batteries nicked, plus a guy about 23 years ago on the GU whose engine & gearbox were stolen! That taught me a lesson.

75k for the batteries if they were new would make my eyes water! As well as the 2 locks on the deck it has locking doors on the wheelhouse, the other problem is one person could lift out the motor and all the control equipment 😟

If I did a narrowboat to electric it would be a trad with engine room to keep it all secure and warm. 

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7 hours ago, Tony1 said:

 

The engine cover boards on my cruiser stern are getting a bit rotten around the edges, particularly the smaller one over the weed hatch, and some time in the next few months I ought to replace at least the smaller one. 

 

I must apologise as I don't know what they are made from- its some kind of ply, coated in a black plasticy film. I think there is a hexagonal pattern on the film, so perhaps it's hexaboard?

 

Anyway, despite the boat having a tonneau-style cover over the stern, which the previous owner would have made use of (in between his periodic visits to cruise the boat), and despite it being about 6 years old, the smaller board is pretty far gone- or at least the outer edges are. 

Seeing how poorly it's withstood the elements,  I don't have a lot of faith in the idea of a wood-based replacement, and I'm wondering about using aluminium chequer plate instead. It'll cost, but it will be a permanent solution. 

 

So I was just wondering- has anyone had experience on a boat with metal engine covers (or spoken to people who have these)? 

Does metal have any serious disadvantages other than cost? 

I can imagine they'll transmit the engine noise more than wood, so I might need another layer of soundproofing, and I can imagine they will be pretty heavy.

The bigger cover is maybe 5ft by 3ft- so maybe I could use two separate sheets to replace that one, to make it easier to lift and manhandle? 

 

I'm tempted to try out a replacement metal plate just over the smaller weed hatch section (about 1ft  x 3ft) , but before spending any cash I'd be very grateful to know if there are any major cons that might present themselves afterwards to spoil the party. 

 

 

Thin alloy plate, non slip where required, is not too expensive and makes good deck or engine covers if supported by plywood. Aluminium does contract and expand slightly more than wood, so alloy some space around the edges for seals or flexible adhesives or sealants. If you decide to go alloy only, it gets expensive real fast, as you are talking thicker panels. Those panels need to be insulated from any steel beams to avoid electrolysis when damp. 

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