Replacing rotten speedboat floor

[Rodg98133]

I am in the process of replacing the soft floor in the 17' speedboat. I have taken the carpet up expecting to find floorboards like on my other boat but i actually found this

I assume this is plywood laminated with glass? How do i go about getting to the rotten wood? Do i just get the angle grinder out and carefully cut through the thin glass to get to the wood? Am i likly going to need to replace the stringers aswel? What should i be looking for to determine whether this needs doing or not?

 

[skipper681]

I just did this in a Fletcher 14, there was angle iron strutts in there below the ply, cut out the floor as best you can, mine was so bad I just picked it off, yep it was that bad. I had to make a cardboard template to cut the floor from. Not a hard job, the transom was another matter though

 

[vyv_cox]

If the GRP is polyester resin based you may well find that it will pull off. I recently replaced something similar on the roof of a wheelhouse. Polyester resin does not bond particularly well to timber and once I had lifted a corner I could easily rip it all off the wood.

 

[skipper681]

I always use these guys for my GRP materials, you should get away with a 5kg kit at £34.50 that will do the floor and still have some left over.

http://www.mbfg.co.uk/

 

[Rodg98133]

Its not stuck to the wood really as the wood is pretty much in pieces underneath but i cant just pull it off as it is bonded to the rest of the boat.

If i get my angle grinder tmoro and just cut a round the sides of the edge of the floor then lift off the glass is that the best way to do it? Will a metal cutting disc be ok or do i need a special disc? Then i will remove the rotten floor and assess from there how much else needs doing.

This sound ok before i start going mad with the angle grinder lol.

 

[ShaunG]

Sounds about right to me, I always use a metal cutting disk (albeit a very worn one to keep control and not cut to deep)

Wear a mask and cover arms neck and as much as possible, the stuff really does itch

 

[skipper681]

Just be careful and try to cut as clean as possible, it's not too hard a job, let us know how you get on.

 

[Rodg98133]

How are the uprights either side held in place as these are wobbly aswel. Will these stiffen up when i put some new boards underneath them?

 

[ShaunG]

I am not quite sure what you mean by uprights...typically (on yachts anyway) the floors (that the floorboard rests on) are fibreglass covered foam or wood. I suspect that the hull attachement of these has broken down, regal assign with exoxy and epoxy cloth would probably fix this..search for posts by oldsaltz..he has a wealth of information on here for fibreglass repairs

 

[Rodg98133]

By uprights i mean these bit circled

 

[gljnr1983]

The side pockets will be tabbed the same way the edges of the floor are done,keep the cut a half inch from the ply edge then dig out the mush and you can see how far back you can take the lip that is left.There will be no wood under the side pockets just fglass so use the half inch method on them to when taking them out.

 

[Rodg98133]

How do i know where the ply floor finishes before i take the glass up? Shall i just cut along the side pockets?

 

[gljnr1983]

If you cut along the inside edge of the slight gully around the flat area you will be ok once you get goin you will have a better idea,the side pockets will be easy enough if you keep the cut half inch from the bottom and finish the corners with a hand saw.
When you have the side pockets dug out the channel you are left with is perfect for sitting the new wood in and re tabbing.

 

[dingdongs]

just seeing the colour of the water in the bilge looks as if your in for the long haul and floor,stringers and bulkheads shot.

http://www.youtube.com/watch?v=uD1rK8Ail2I

watch these in order for a good diy in replacing floor.

 

[rob2]

Looking at the photos, I'd have to say that one man's guess may be as good as another's. There will be a certain amount of "suck it and see". I would councel you to consider replacement of parts as beng easier and quicker than repairs. I've tried scarfing bits of ply into a panel to repair wet areas and it often proved better to take out the whole panel and put a new one in.

I'm not convinced that the colour of the bilge water is a reliable indicator, if rain has been collecting with a few leaves about, that's exactly what it looks like! Bear in mind that the original construction will have been in polyester resin, which unfortunately doesn't bond all that well with wood, so even if the panel isn't sodden, it may have delaminated from the GRP skins and will feel springy. Having said that, once you open it up you may as well start with new ply, glued down with epoxy. Also worth giving the panel a coat of epoxy, especially the edges, to seal it and ensiure it bonds well. You can either epoxy the original GRP skin back on or simply lay up a new one using glass cloth and epoxy. On canoes, some people use a graphite powder in the final epoxy mix to give a harder finish, but you may as well paint it over with Sandtex to give a non-slip and bullet-proof finish even if you're going to carpet over it.

If you're sure you're going to do it, then be bold but with a thought as to how your cutting will affect the rebuild.

Rob.

 

[oldsaltoz]

I am in the process of replacing the soft floor in the 17' speedboat. I have taken the carpet up expecting to find floorboards like on my other boat but i actually found this

I assume this is plywood laminated with glass? How do i go about getting to the rotten wood? Do i just get the angle grinder out and carefully cut through the thin glass to get to the wood? Am i likly going to need to replace the stringers aswel? What should i be looking for to determine whether this needs doing or not?

G'day Rod,

First question: are you planning to keep her for some years, if not it may not be worth repairing.

If on the other hand you plan to keep her my advice would be to replace the whole floor, the problem with only doing the soggy bits is that there will already be other areas that develop into more soggy bits because it was never done properly in the first place.

If the stingers and ribs are made timber and glassed over they should all be removed because the timber inside will almost certainly be mush. This method is no longer used in construction because the raw or poorly coated poly resin and glass are not waterproof, and the timber is a structural member with the glass just holding it in place, so when the timber rots it weakens the hull.

This old school system has been replaced with Epoxy resin and cloth over a foam profile, it's the Epoxy saturated cloth that provides the strength.

I would first make sure the hull is well supported and she lines up, before you start cutting, because she may change shape and effect future performance.

Then remove the floor completely and replace it with more ply. Also grind out any remaining stringers and replace them with an oval foam former and Epoxy resin/cloth.

Do Not use any expanding foam to fill the hull below the floor. it may hold water, may rot the underside of the floor or just fall apart. I believe all small power boats should have built in buoyancy and the cheapest and reliable method is to fill the void with pool sticks, no the from the local snooker hall, from the local swimming pool. They last many years out of the sun, do not take up moisture, and will allow drainage when you take the bung out.

To prevent the new ply going the same as the old stuff, get the warm (sunlight is good) and apply at least 3 coats of epoxy resin with no additives to ply, do this in one go by applying wet on tacky and save yourself a lot of sanding and cleaning up. Make double sure you give the edges (exposed end grain) as many coats is it will take, it will look smooth when it's full, the resin will get drawn unto the end grain, so just keep up to it, this the place most moisture gets in.

When installing the floor, make sure it is in the right place, measure all round to confirm this, then fill the gap/s between hull and floor with a mix of epoxy resin and Micro-fibres mixed to about peanut butter consistency, thin enough to work with but thick enough to not run down into the hull.

Get hold of a small round object like a small fish paste jar and form a coving between the floor and the hull, keep it smooth because you will applying cloth over this to tab the floor to the hull, no nasty corners to clean and very very strong.

Keep us all posted on you plans and progress.

Good luck and fair winds.

 

[Rodg98133]

Right good news and bad news....

Have taken most of the flooring up and all seems ok (except the floorboard obviously) the stringers and bulkheads are solid as solid can be.

Now for the bad news....

I went and cut through the bottom of my b@£&ard hull!!!!! What can i do? Is this going to be easy enough to repair? I know you will all tell me that if i dont know what im doing then dont do it but its done now and i need a solution lol.

Help

 

[oldsaltoz]

I went and cut through the bottom of my b@£&ard hull!!!!! What can i do?

Pretty simple repair even for a novice provided you can access both sides.

Have a good look at the cut to get some idea of the hull thickness, this will help determine how mack material you will need to carry out the repair.

Using an angle grinder with a concrete grinding disk rated at 40 grit, grind out about half the thickness from both sides.

Or only the underside if access is poor.

You should end up with a concave slot about 4 inches wide, extend the ends just past the end of the cut by about 1.5 times the width.

Wash the area some Acetone and white cotton rags.

Cloth, resin and other materials.
Epoxy resin and cloth designed for use with epoxy resin, look/ask for a multi directional cloth (crows foot) 300 gram should be a good thickness for this job. also get a couple of strips of rovings (cloth) to give a smoother finish (last coat). More on this further down.

Micro-balloons or glass spheres, this is a filler that is mixed with the epoxy resin and used to fair the repaired area, micro-balloons are easier to sand but glass spheres are stronger and more waterproof, being made of glass rather than resin as in the micro- balloons. But the glass spheres are a little to sand back, but worth the effort.

Tools:
A grooved roller as least 2 inches wide, a few 1/2 and 1 inch brishes, a sheet of builders black plastic about 1m square. scissors, wide shallow containers, like 1 litre Ice cream containers x 3. some white vinegar, and Acetone. sandpaper, 100 grit and 250 grit. Latex disposable gloves (100 in a box is about $7.00AU. Put two gloces on each hand, so if/when things get a bit sticky, you peel one off without stopping the job.

Weather conditions:
Temperature above 18*C and Humidity below 73% for the first 6 to 8 hours after application of the resin.

Methodology:
After grinding (we will assume we are doing one side only, repeat for both sides)
Clean the area with Acetone to remove all dust and any contaminats from grinding.
Pre cut you cloth strips, note the first strip will be perhaps an inch or so wide, the next perhaps 2 inches, the aim is to fill the concave void in layers getting wider as you work your way out, if you develop a hollow, add a thinner strip to fill it, or two thin strips on the outer low sections if it starts to crown.

You can wet out several layers on the builders plastic and brush some resin onto the repair and lift the thicker layer off the plastic and lay it into the repair, this method is for overhead work only.

Continue laying the strips till almost flush, then add a strip or two of the rovings.

Important: You are looking for a ratio of one to one resin to cloth by weight, so keep that grooved roller Woking and make sure the cloth is fully wetted out, any light colour is an indication of dry cloth or trapped air, get rid of it OK. not enough resin will make a weak job that will fail, too much resin will have the same end result.

after curing for 24 hours, try the thumb nail test, if you can mark the resin by pushing you thumb nail hard into it and it leaves a mark, it's not fully cured. So wait a bit longer.

Epoxy resins can leave a deposit on the surface caused by the curing action, this must be removed before any sanding. it's as simple as running a hose over the area and rubbing it with a plastic kitchen scourer (Scotch-Brite) till the water no longer forms beads like on a freshly polished car.

Let it dry and give it a quick with some Acetone, sand off any high spots with the 80 grit paper then sand the rest to provide a key for the filler using the 250 grit.

Now mix about half a cup of resin and hardener and cover the area to be filled with resin, just brush a bit on. Then add some Balloon or Spheres to the remaining resin and mix to toothpaste thickness, apply this over the resin coated areas and smooth it out with an old plastic ruler or other flexible tool, make sure ther are no low spots or you be doing parts or the job again. Allow to cure for 24 hours.

Before sanding, clean the area as above, sand smooth to the hull rady for top coating, add a layer or two of resin when you are happy with the finish and let it cure, clean again as above and lightly sand to provide a key and coat with a high build epoxy primer, let it cure, wash as above and coat with some Flow coat (Flow coat is the same as Gel-coat but has wax added so no need to cover it with plastic to exclude the air) Let it cure and take her out for a run, you desrve it after all that.

I'm sure to have missed something, used about 18 litres of resin myself today and all inside work so the brain is still fuzzy. any questions ask away.

~ ><((((º> <º}}}}>< ~


Good luck and fair winds.

 

[Rodg98133]

That all sounds rather easy :-/ How much would i be looking at for a show to do this work for me? I was kinda thinking to grove it out from the inside and put quite a few layers on fibreglass mat and resin then when this has hardened put some epoxy into the crack from the outside.

Would this not be strong enough? I've never done fibreglass work before but at the same time its not worth spending loads on it as its an old boat and i will probably only have it for a season if not less.

 

[oldsaltoz]

That all sounds rather easy :-/ How much would i be looking at for a show to do this work for me? I was kinda thinking to grove it out from the inside and put quite a few layers on fibreglass mat and resin then when this has hardened put some epoxy into the crack from the outside.

Would this not be strong enough? I've never done fibreglass work before but at the same time its not worth spending loads on it as its an old boat and i will probably only have it for a season if not less.

Standard Poly resins do not adhere very well to old poly resins, hence the use of epoxy resin.

Sounds like you have good access from inside, just remember to tape the underside first, or better yey apply a couple of layers on the unerside first and let them cure.

Good luck and fair winds.