Thread: Hartley 16 - "Touchwood"

Is it a fibreglass hull? Gelcoat means a fibreglass hull.

If it is a fibreglass hull It is a lot of work to fix a few hairline cracks and it is a lot of hard work to produce a nice result.

Patching doesn't work well either because of the colour differences ... the boat will have to be repainted and the paint system that makes sense for a really good job is Two Pot.

In general I would suggest not starting the job unless you are really ready to do all the work to resolve the problem.

The biggest problem is that the gelcoat is not very elastic compared to the rest of the structure. So over time it stars getting those fine cracks. They have almost no structural impact.

However you do have to remove all the gelcoat or whatever you put over the top will crack in exactly the same places - you have to remove the cracks completely.

Gelcoat is quite thick and you have to grind it off so the cracks are gone. Then you have to build up to the original surface. If you don't get it precisely right then it will look worse than it does now.

That's the problem.

If it is a wooden boat with cracking, you still have to remove the cracked paint - the reason smoothing is not a problem is that paint is relatively thin and there is plenty of warning when you hit the wood substrate so you never lose the original smoothness.

Best wishes
Michael.

Thanks Michael,

So gelcoat is fibreglass eh - my bad. One of my mates told me it was gelcoat, but you cant trust ya mates !!

So its a wooden boat with nice thick gloss paint then ? Perhaps the Two Pot you mention ?

My concern is the degree of rot that may be present in the wood/plywood sheets on the hull ?

If I sand the paint off, how will I know what needs to be dryed out versus what is too far gone ?

Cheers.

Howdy ... these little cracks along the grain closely spaced are called checking. Is it generally over the hull or just in a few well defined areas?

To find rot you go round the boat hitting it with the plastic handle of a screwdriver. You will hear a change in the note if it is rotten. Ting Ting Ting Thud. See how far the thud goes .. use the pointy end of the screwdriver to see if it sinks in easily on the thuddy bits ... look from the inside too. If locate Thuds or soft spots follow all the bits of timber close to see if it has travelled up them.

The typical places are up around the transom and up inside the bow, around the deck edge, down the middle of the foredeck, the ends of the deck beams. Maybe around the centrecase. Near the centreline.

The thing is to assess the exact extent of the various problems then make a decision about what to do. If you dont' plan beforehand then the job will get bigger and bigger and you will be sailing in 2020 or selling a half repaired boat about the same time!

I had a plywood racing dinghy with the checking problem too - assuming it matches the description above. There is only one para about the hull repair and painting ... I did use very light glass to deal with a couple of areas of checking too. I use a sander to cut through the paint and cut into the first veneer a little - then the very light glass is laid in. This prevents any further checking. I need to describe it better but once you ascertain the actual condition we can look at a repair strategy.

Q&A How to Race a Dinghy Successfully - Michael Storer Boat Design

MIK

Originally Posted by sv_touchwood

If I sand the paint off, how will I know what needs to be dryed out versus what is too far gone ?

Marty,

I am sure others will 'chip in' with more advice very soon but here goes for a start!!

Nice looking little boat by the way!!

Start by removing the paint where the cracks are first. Once you have this removed right down to the bare wood you will soon know if there is anything underlying (ie: rot) that will need further work......having repaired a number of ply hulls with rot myself now, I can assure you it will be quite obvious if there is rot there. If you do discover further damage then take some photos and post them up here for all to add their advice for your next move. Hopefully it will be nothing more than a few cracks in the paint finish and you may get away with just a repaint of the hull.

Actually.........looking at your photographs again.......it looks beyond rapair.......just ship it over to me and I'll get rid of it for you!!!! (Hehehe!!)

Cheers,
Vern

Vern & Mik,

Thank you both for your time & comments.

I will do some sanding, and post some pics of what she reveals...

All the best, Marty

no ... how extensive is the checking ... is it in defined areas or is it general ... and is there any rot?

MIK

The cracking is mostly on the starboard bow, as shown in the pic...

The boat has 2 repairs as shown in the other pics, one on the port chine, and the other along the centreline on the port side.

From the inside, the hull looks pretty good. I certainly cant see any rot.

I did the end of the screwdriver test, especially on the starboard bow - all I could hear was the note change as I came across the frame spars.

All Good news then!

It is checking. It is either localised inside one piece of ply or that corner is the one that has been exposed to the sun and/or weather.

It looks like it is just one area.

The dark colour might be to blame too - heating up the wood is not good for the wood or the paint.

Checking is in the wood, so if you paint over the top the checking will reappear usually. However a layer of VERY LIGHT fibreglass cloth can fix the problem and not leave a bulge on the outside of the hull.

If the boat doesn't have a huge buildup of paint I would not strip it generally - too much work for the result. If it needs it generally, then sure ... repaint the hull.

But what you do with the checking is

sand that area back to bare wood Start coarse, but when you see timber change over to about 100 grit - no coarser as it ruins the adhesion of whatever follows. Use a flat pad sander like a random orbit or orbital. Dont ever touch the hull of a boat with a disc sander! A belt sander in

Sand a bit further to remove some of the first veneer .... a good controlled way is to draw pencil marks cross hatched over the plywood surface then work over and remove them all. Keep the sander flat - don't let it dig in. Spend the same amount of time on each area and take about 20 minutes to do the whole thing.

You don't want to go through to the veneer below so you have to watch for that. The first sign you are getting close is some really fine black streaks in the wood grain which is the glue that has seeped through into the surface veneer, but is best to keep well away from even this.

You should get about a cup of fine sawdust from the process.

Now just sand the paint away a little wider than the area you just prepared. maybe an extra 20mm just to bare the plywood.

Now you need to get some 75gsm (2oz) woven glass fabric. A lot of places don't sell it that light and will try to talk you into something they want to sell you. Around 75gsm or lighter will work. Must be a smooth woven cloth.

If you can't get it locally get it from Duckflat or someone else who will post stuff out.

Get about a litre of epoxy.

Use the method here for the glassing. You will need to cut the piece a little oversize - maybe 50mm all round - beyond the sanded edge then use masking tape to hold it in position along the top edge. As it is a beyond vertical surface using a small epoxy roller makes the most sense. Get the epoxy on the surface starting from the middle and working out and worry about getting it smooth later ... you want it out of the container or the heat will build and it will go off on you. Once it is on the surface you have time to get it right.

The light cloth wets out very easily. Just apply resin over the area that is bare plywood.

Work from the middle towards the outside edge. When the glass goes clear enough to see the wood grain under clearly it is wet enough.

Stop, put the roller in a plastic bag in the freezer.

Test the epoxy on the boat. when it starts feeling sticky then mix more pox and roll on another thin coat to fill the weave. Don't put a lot on ... just one smooth even coat.

Wait for it to go tacky again and repeat until the surface has become filled about 90%.

Let the epoxy cure.

Sand the area lightly so it is matt - about 180 grit paper - you don't want to cut into the glass fibre much so just matt. but work hard around the edges where it laps onto the paint to get a smooth transition.

Mix up epoxy and a lightweight easy to sand fairing powder into a consistency a little thinner than peanut paste and use a squeegee of plastic or plywood with a smooth sanded flat edge to apply a smooth boat over the area. Let it cure.

Quickly sand the worst of the lumps and bumps off the surface with the orbital. Then you need a sanding block that will take half a sheet of sandpaper 120 grit maybe - the block needs to be teh length of the sandpaper sheet. Hold it flat and use about long strokes to fair off the surface. you will find there are angles where the block will sit flat on the surface along its longitudinal axis. Keep it at that angle but don't sand in that direction. Sand laterally or at about 45 degrees to that lie down flat angle.

When it is all smooth you can undercoat it and paint it. Because of the dark colour of the paint it will be impossible to match colour ... so get it close, then sand the whole thing and put one coat over the lot.

You might need a second.

Or you could sand the whole hull more heavily and paint it a lighter colour which would be gentler on the hull if it is stored outside.

Best wishes
MIK

Mik, wow man, thank you very much for this detailed response. I truly appreciate it.

If I proceed with a new colour I will certainly go with a white I think. Should look nice...

I'll let you know what happens.

All the best, Martin...

No worries Martin.

Give us a yell here if you need any other info.

MIK