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I'm about ready to put down bearers for the floor in the fore cabin.

I suppose I could arrange them as per the old ones I've removed, but maybe there's a better way...? The old ones ran 'athwartships', from the keelson to the hull side (not fixed, but wedged in tight) along the angles welded to the hull bottom. There are gaps/holes at the ends of the angles, but the old bearers made for a water trap.

(hope the photos make sense of this - first pic is looking towards the stern, second towards the bow with all the crap stowed under the foredeck)

Have bought lengths of 2x4 - the height of the keelson is just less than the width of the timber. The original floor sat on top of the keelson, but I think the new one should sit a little higher with a gap between the floor and the top of the keelson.

Any ideas / standard practice?

Cheers!

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Don't know if this helps but as far as I can tell on my boat the floor bearers look like lengths of 2" x 3" running the length of the boat but mine seem to be sitting on the base plate. I think they are on about 18" centres. My floor feels very firm. If you did it this way they could sit on top of the cross members. I think the floor would hold them in place once screwed down.

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Your angles are the wrong way round! They should be welded with an edge to the hull plating, so there is a free flange parallel to the plating. Your floor bearers would then sit on this, clear of any bilge water.

Also,  they are too far apart to provide adequate support.

So I would support the bearers on short blocks of wood, resting directly on the baseplate and spaced no more than 18 inches apart.  The bearers can then run either way, and there will be space for any bilge water below the main bearers. For the blocks you should use treated timber as they will be prone to rotting.

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You could use 4"x2" running parallel with your keelson but slotted to fit over the bearers, and glue wood to the keelson to level it up. At least that way you would keep the timber away from the base plate and achieve a strong framework for your flooring, it will also leave the floor at a reasonable height.

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On 5/16/2017 at 17:54, Sir Percy said:

I'm about ready to put down bearers for the floor in the fore cabin.

I suppose I could arrange them as per the old ones I've removed, but maybe there's a better way...? The old ones ran 'athwartships', from the keelson to the hull side (not fixed, but wedged in tight) along the angles welded to the hull bottom. There are gaps/holes at the ends of the angles, but the old bearers made for a water trap.

(hope the photos make sense of this - first pic is looking towards the stern, second towards the bow with all the crap stowed under the foredeck)

Have bought lengths of 2x4 - the height of the keelson is just less than the width of the timber. The original floor sat on top of the keelson, but I think the new one should sit a little higher with a gap between the floor and the top of the keelson.

Any ideas / standard practice?

Cheers!

I'm trying to work out what that means.  A keelson is a longitudinal strengthener, the above highlighted sentence doesn't make sense, to me anyway. 

22 hours ago, BWM said:

You could use 4"x2" running parallel with your keelson but slotted to fit over the bearers, and glue wood to the keelson to level it up. At least that way you would keep the timber away from the base plate and achieve a strong framework for your flooring, it will also leave the floor at a reasonable height.

That's a good idea, though it's hard to tell how for apart those angles are 4x2 should do it.  Having the timber bearers on the baseplate isn't a good idea.

Presumably this was a originally a cargo carrying hold so the floor wasn't designed to accommodate underfloor ballast?  

   

 

 

 

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58 minutes ago, Neil2 said:

I'm trying to work out what that means.  A keelson is a longitudinal strengthener, the above highlighted sentence doesn't make sense, to me anyway. 

From the context I think he means that the keelson is a little less than 4" high. 

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That's helpful, thanks. Looks very steampunk!

 

22 hours ago, Neil2 said:

Presumably this was a originally a cargo carrying hold so the floor wasn't designed to accommodate underfloor ballast?  

Presumably, don't know. The floor would have been put in at some point afterwards, I think. Paving stones underneath.

 

 

Edited by Sir Percy
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22 hours ago, Neil2 said:

That's a good idea, though it's hard to tell how for apart those angles are 4x2 should do it.  Having the timber bearers on the baseplate isn't a good idea.

Hows this for an off the wall suggestion.

If the longitudinal floor bearer slotted t fit over transverse metal upstands is adopted how about sitting the floor bearers on a line of plastic "cross" floor tile spacers? They could be alternately displaced slightly to each side side to support more of the width of the bearer.

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2 hours ago, Tony Brooks said:

Hows this for an off the wall suggestion.

If the longitudinal floor bearer slotted t fit over transverse metal upstands is adopted how about sitting the floor bearers on a line of plastic "cross" floor tile spacers? They could be alternately displaced slightly to each side side to support more of the width of the bearer.

 Only today, I've been putting sections of steel reinforcing mesh (for concrete) on my base plate to support the ballast above any water that might sneak in.

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17 hours ago, Tony Brooks said:

Hows this for an off the wall suggestion.

If the longitudinal floor bearer slotted t fit over transverse metal upstands is adopted how about sitting the floor bearers on a line of plastic "cross" floor tile spacers? They could be alternately displaced slightly to each side side to support more of the width of the bearer.

Here's an even more wacky idea.  There's a form of house floor construction known as a "floating floor" where there are no floor joists, polystyrene blocks/sheets are laid direct on top of the concrete screed, then floor panels, usually chipboard but they could be plywood, laid on top.  The wooden floor literally floats on top of the polystyrene.  On a boat with no angles to fix bearers to this would be feasible and the floor would be well insulated to boot.  I think the main disadvantage would be in the case of a flooded bilge the water would have nowhere to go, though you could incorporate a certain amount of void and have an automatic bilge pump at the stern.  

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24 minutes ago, Neil2 said:

Here's an even more wacky idea.  There's a form of house floor construction known as a "floating floor" where there are no floor joists, polystyrene blocks/sheets are laid direct on top of the concrete screed, then floor panels, usually chipboard but they could be plywood, laid on top.  The wooden floor literally floats on top of the polystyrene.  On a boat with no angles to fix bearers to this would be feasible and the floor would be well insulated to boot.  I think the main disadvantage would be in the case of a flooded bilge the water would have nowhere to go, though you could incorporate a certain amount of void and have an automatic bilge pump at the stern.  

When our family's holiday cottage was flooded, the floating floor --- floated! With sufficient strength to upend a tall fridge freezer.

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I think the best way to do the floating floor idea would be to have the insulation blocks bonded to the base plate with something that won't melt them, spaced 2" apart to permit water flow. Then the plywood bonded to the blocks. The disadvantage of using plywood instead of flooring grade chipboard is that the latter is tongue & groove which, when glued together, makes for a solid slab of a floor. Plywood would tend to move around at the joints unless it had some other floorboard nailed down on top of it. 

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2 hours ago, system 4-50 said:

When our family's holiday cottage was flooded, the floating floor --- floated! With sufficient strength to upend a tall fridge freezer.

This is in fact the big disadvantage of the system. When I was involved in the flood damage business I was called out to a similar situation where a simple leaky pipe joint had discharged enough water to fill the "void" and lift the chipboard floor which had turned into a mushy mess in the process, you could stick your finger right though it yet the house owner hadn't suspected a thing.  

2 hours ago, WotEver said:

I think the best way to do the floating floor idea would be to have the insulation blocks bonded to the base plate with something that won't melt them, spaced 2" apart to permit water flow. Then the plywood bonded to the blocks. The disadvantage of using plywood instead of flooring grade chipboard is that the latter is tongue & groove which, when glued together, makes for a solid slab of a floor. Plywood would tend to move around at the joints unless it had some other floorboard nailed down on top of it. 

That's a good point, though if you laid the ply in sheets front to back, unless it's going to be open plan, presumably you could employ the partition walls, fixed furniture etc to bond it all together.      

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23 hours ago, Tony Brooks said:

Hows this for an off the wall suggestion.

If the longitudinal floor bearer slotted t fit over transverse metal upstands is adopted how about sitting the floor bearers on a line of plastic "cross" floor tile spacers? They could be alternately displaced slightly to each side side to support more of the width of the bearer.

The thought of a larger lady in stiletto heels pops into my mind.

Anyway, about your wacky idea...

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31 minutes ago, Sir Percy said:

The thought of a larger lady in stiletto heels pops into my mind.

Anyway, about your wacky idea...

I do not understand what a large lady in stiletto heels has to do with it.

It was suggested that  lengths of 4 x 3 floor bearers running the length of the boat be slotted and fitted over mental cross members. I do not like the idea of wood sitting directly on a painted or unpainted base plate because of it trapping water and encouraging rust so I suggested raising the bearers on the tile spacers. The actual floor would be fixed to the bearers. The person who specifies the floor shoudl think about the large lady but a combination of the floor and the bearers will spread any point loading meaning there would be a comparative low compressive force on the said spacers. This may not hold true if only a few spacers were used along the length of the boat but I envisage 3 or 4 to the foot.

I'd much rather use comparatively soft and inert plastic than rust prone and very hard reinforcing steel but that's a personal choice..

Edited by Tony Brooks
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On 2017-5-16 at 20:03, system 4-50 said:

 

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Is that a sprayfoamed baseplate that the ballast is sitting on?

I'm not sure if that's a great idea. There's bound to be gaps at edges where water will get underneath and won't drain. Also if a puddle of water sits on top of sprayfoam for long enough is may penetrate and waterlog the foam. Plus the weight of the ballast will eventually cause "creep" (long-term compression) of the foam meaning it loses some of its insulation properties.

Personally I think it's better to paint the inside of the baseplate with few coats of a good two-pack epoxy, lay the ballast on something that raises it a few mm above the baseplate (old cables, plastic spacers, etc) so that water can drain, and if you want insulation it should go between the ballast and the underside of the floor.

Edited by blackrose
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Just now, blackrose said:

Is that a sprayfoamed baseplate that the ballast is sitting on? Yes

I'm not sure if that's a great idea. You're not alone. Many people are not sure. There's bound to be gaps at edges where water will get underneath and won't drain. What water? 7 years so far & very little water (that I've found) so far. A couple of window leaks & a bit of condensation on a foam miss. I'm not sure how easily water can get under it, its quite a good bond.  Also if a puddle of water sits on top of sprayfoam for long enough is may penetrate and waterlog the foam. The foam is much more robust than the stuff you get out of can and has a hard skin that you can stand on without damaging it. Also I have put a lot of work into avoiding the possibility of water system leaks. Water seems to just sit on it. Plus the weight of the ballast will eventually cause "creep" (long-term compression) of the foam meaning it loses some of its insulation properties. After 7 years, not the slightest indication of that with engineering bricks. I've replaced some of them with iron blocks, we'll see how they do.

I happily accept that it may turn out to be a disaster but there is no sign of it yet.

My problems are elsewhere: 

  • Rust on bits that were missed when the boat was spray painted by the builder - very few, one inside an RSJ in the engine bay, another under the gunnels on the well deck.
  • Condensation on bits missed by the foam sprayers - I didn't check their work properly, leading to rust.
  • Leakage from the hatch and windows and window condensation. Some of this is my own fault.

 

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I agree a bit of condensation etc isn't a big deal I think the real reason to have a proper void in the bilge is in the event of a flood when it might compromise getting the bilge properly dry.  But most narrowboats will have this problem today I guess.  I looked at a boat a while back that had problems with the calorifier leaking.  The owner said it happened over a year ago but there was still water in the bilge because it was shallow and the ballast was laid straight on the baseplate.  That was the price he paid for a boat with a lot of headroom. 

There's a lot to be said for the old wet bilge design where the ballast was laid on longitudinal angles about 2" above the baseplate so any water could flow freely to the stern but you do end up with less headroom and you do have to use slabs rather than bricks, for example.        

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  • Most of my water pipes joints are "guttered", that is to say, if they leak they leak into a gutter that drains into the shower tray. This would not cope with a "powered" leak.
  • The takeoff from my water tanks goes up through the top rather than out of the side. This would still not prevent a "siphoning" leak.
  • The cauliflower is in the engine bay so a leak there is unlikely to reach the cabin unless powered.
  • I won't be happy until I have removed every possibility of a powered leak. This may take some time yet.
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44 minutes ago, Detling said:

The trouble with t & g chipboard is that if you ever have to lift it you end up wrecking it.  Don't ask how I know, I now have ply screwed down which can be lifted and put back down.

You probably wouldn't use chipboard on a boat but there's plenty of laminated flooring out there and it's the same principle only worse.  Even if you can salvage a section of floor you probably won't get a new one to match up.  I once had to remove an entire kitchen/lounge laminated floor about 30x15 foot just because of a leaky washing machine.  Apologies to anyone who has it but I think laminate flooring on a boat is a terrible idea.

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