Advise on replacing deck on 1970 crusier

[Fraggle]

Could anyone advise on the thickness of marine ply suitable to replace deck on a 1970 river crusier. I am unsure whether to use 12mm or 18mm. Any advise would be appreciated. Do not want to add excess weight if its not required.

 

[Twister_Ken]

Drill a hole in existing, and measure?

 

[exfinnsailor]

Don't use cheap ply . You need at least 5 ply . Anything else will have a layer on the outside and a load of rubbish inside . Look out for voids and soft spots . Decent QUALITY ply is not cheap , especially if you call it MARINE PLY

 

[sailorman]

Don't use cheap ply . You need at least 5 ply . Anything else will have a layer on the outside and a load of rubbish inside . Look out for voids and soft spots . Decent QUALITY ply is not cheap , especially if you call it MARINE PLY

in the trade i have never heard of or used the term "5 ply "

 

[PCUK]

12mm will be OK as long as it is well supported. Buildbase builders merchants do a very good all-hardwood exterior ply for about £20 a sheet.

 

[DownWest]

As it is a river cruiser, and if the support beams are reasonably close together (12"?) then 12mm should do it. Google marineplyonline they are near Bristol and much cheaper than a better known firm there. Cors, if you have large crew members leaping onboard from high locks, then a bit thicker might be an idea.... 18mm is pretty thick tho. My sea boat has 10mm on 12" framing. But in effect, this is 9mm because 10 is rare nowdays. Designer said 'not a problem'.

Edit: slow typing: PCUK got in ahead.

 

[Fraggle]

Thanks for advise. Exisiting frame is 18" apart. As this is a high traffic area i.e getting on/off/ social area I thought thicker the better (within reason!) but i was worried about compromising boat structure.