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| T O P I C R E V I E W |
| LenB |
Posted - 03 Jul 2011 : 18:45:05
At last I have started to renovate my Norman 18, I took a horrible "U" shaped lump of metal off the transom and found to my horry it was all hacked away and the ply between the outer skin had turned to black damp dirt. The inner thicker ply seems to be not too bad.I have drilled three large drain holes in the bottom of the transom and some water has drained out. Short of cutting the whole outer skin out, any one have any ideas?
I thought that after I have got the dirt/rotted wood out of the back outer section I would glass a new piece of ply in, and fill the void either side with expanding foam, and also drill vertical holes into the good wood and fill with epoxy resin, the re glas the transom over and fit a stainles steel engine bed plate. What do you think?
I'm going to be using a 30hp two stroke Suzuki weight about 170lbs.
Len. |
| 8 L A T E S T R E P L I E S (Newest First) |
| LenB |
Posted - 05 Jul 2011 : 10:13:05
I have almost done it, well done the hard bit, I made up two "J" shaped rods and ground a chisel end, one 6mm and the other 8mm with these I was able to pull out all the wood/mush on the outer panel, the inner (shorter panel) I drill down into the wood with a 13mm drill, with a chisel and the aid again of the "J" rods I got all the wood out.I washed both voids out with a pressure washer till the water ran clean. When it has dried out I will replace with bounded in marine ply, the parts I can't get to I am going to inject resin and glass beeds. I have take advice on this from our local fibre glass specialist.
Len. |
| greenmills1314 |
Posted - 04 Jul 2011 : 22:40:25
All sounds very familiar. I found the transom on my 23 totally rotton probably due to the 33 holes put through it over the years. The only solution was to grind out the inner skin, remove all the rotton end grain balsa infill and do a rebuild, firstly glassing in the holes then replacing the wood with lots of end grain pieces cut on a chop saw and covering the wood with two thicknesses of 600 glass mat, the splash well was missing making the task easier, this has now been replaced as part of the rebuild, incorporating another thickness of marine ply where the engine will clamp. It was'nt too big a job in the end so good luck with what you decide to do.
Paddy
Clanky tiff |
| stratford4528 |
Posted - 04 Jul 2011 : 18:56:53
Mike mentioned polyurethane glue.I am refitting my 32 with ceder and I use polyurethane glue from Tool station which is £9-11 for 750g. It is resistant to salt water and sticks to fiberglass very well. |
| mike |
Posted - 04 Jul 2011 : 13:20:29
I seem to remember somewhere that Normans did not have plywood in the transom void but wood blocks with the end grain fore/aft. All to do with the wood expanding and contracting less and not trying to seperate the inner and outer transoms.
What are you planning to do with the boat? If you are only going to use on inland waters then the transom will not need to be as heavily engineered as you would for a seagoing boat.
Either way you need to remove ALL the rotten wood. To do this it is probably best to remove - CAREFULLY - the inner transom and after cleaning and drying make plywood panels to fit in behind the outer transom. Its best to make several panels of thin ply as there is a slight curve to the transom and you need to get the ply tight and well bonded to the transom -use resin, hardner and filler powder to give a light paste, its probably best to bolt through to give a tight fit, you can always remove and fill the bolt holes later when its cured.
Then as you fit the next ply panels use polyurethene glue, (JoinersMate, Gator Glue etc) it expands and fills minor voids. You need to make sure that it is evenly coated over the whole panel and probably screw the second panel to the first to keep the curve, you then carry on adding panels till you get the required thickness. It seems complicated but the transom has a slight curve to it and doing it this way means that your plywood has the same curve and is well bonded.
Good Luck Mate
However you do it its not a Saturday afternoon job.
Mike |
| Jimbo |
Posted - 04 Jul 2011 : 07:23:36
Fair comment Cliveshep. However the removal of all rotten wood and allowing the cavity to dry out will be a pig of a job. On my Birchwood you are correct that the fibreglass transon is single skin. However Bering an inboard engine I had to remove the gear leg and engine as well as all seating framework to give access to the rotten transom's wood. Problem in all cases of transom replacement is how far has water ingressed into the hull stiffeners. I have heard of Norman owners who have carefully cut away the outer fibreglass transom to provide access. This can be glassed in after repoair anyway. Best of luck any way. |
| cliveshep |
Posted - 03 Jul 2011 : 22:33:35
I don't know what the layout is on your Birchwood Jimbo, but presumably a transverse seat arrangement? The Normans have the timber glassed into the transom, then the topsides c/w motor well (all in one piece on later models is glassed to the hull moulding, and finally the cockpit locker/floor moulding is glassed in. All of this lot is bonded to the reinforced transom creating the structure.
Replacing the transom timber is well nigh impossible without cutting half the boat away.
The cost of boating is insignificant compared to costs of a young wife and two teenage kids! |
| Jimbo |
Posted - 03 Jul 2011 : 21:46:33
I think that the suggestion from Cliveshep is of merit but does not deal with the whole problem which is to remove ALL rotten wood. I have just replaced the whole transom on my Birchwood 25 widebeam and the only way to complete this repair was to remove all of the inner transom wood. I accept that there was no fibreglass inner transom wall only 1 1/2" of marine ply which was removed carefully with the aid of a 2" wood chisel and mallet. DO NOT try to lever any infill off otherwise damage will occur to the fibreglass hull. If you have an inner and outer fibreglass skin with a wood infill I would still be inclined to remove,by cutting, the inner fibreglass skin so that not only will you remove all rotten wood but allow time for the whole area to dry out. You will probably find that water has crept between the transom and ant longitudinal strengtheners at the hull bottom. If so drilling a few small holes will help to drain ouit the water. I was still getting water appearing up to 4 weeks later. When all is dry replace the transom wood with either Marine Ply--very expensive; only obtained in 8ft x 4ft sheet at £50 a time. I used concrete shuttering ply because it was a little cheaper but both sides were coated with a phenolic resin coating which is waterproof. Scuffing up the coating enabled two pack polyester resin to bond together ans to the glassed into to transom. Glass matting was usedalong the sides and bottom. Do not glass the top because that is where you keep pouring the resin in, in 1/2 to 1 litre quantities.
When no more resin is accepted and the transom is starting to cool down then glass back in the fibre glass inner that you cut out previously. Although this seems a long drawn out job you only want to do it once so do it properly. |
| cliveshep |
Posted - 03 Jul 2011 : 19:46:37
What I think is you are not going to like what I think!
You ideally need to replace the transom which is a bit of a chore!
Look under the motor well - the transom ply goes from side to side of the boat and behind the motor well moulding and the cockpit locker moulding and is glassed into the hull at the transom. If it is in two layers and the outer one is rotted then perhaps you can winkle enough of it out to get a decent piece in spanning past the motor well sides. Pour in some resin to wet everything down and force it in assuming the inner piece is in fact dry enough to take a bond with resin. Otherwise it's hack out the whole lot and re-glass it in. It has to be strong and filling it with foam and body filler might make it solid enough to resist the motor clamps squashing it but it will have little or no resistance to the motor trying to rip the whole lot off the back of the boat.
Just thinking about what I'd do in similar drastic circumstances I think Id be inclined to use a long drill bit, say 1/2" diameter, and use it to drill out the transom from above trying not to damage the outer hull in the process. I'd want to make sure I created a half inch wide vertical slot which is what I'd be trying to achieve at least 4 inches deep and as far beyond the motor well sides as possible. It would mean working a twist drill pretty hard from side to side and blowing the dust out of the resultant slot but that is doable.
Then I think I'd go and buy some 10mm high-tensile reinforcing bar, (as used for concrete work) and cut that into appropriate lengths, probably 8 - 10 of them, pour polyester resin into my slot and drop 2 or 3 lengths of re-bar down into it and let the resin find it's own level and gel a bit. Then Id mix and pour another batch and drop in more bars and so on until I got to the top of my slot. I'd be figuring that once the resin cured around the lengths of re-bar I'd have a pretty tough and strong transom unlikely to ever fail again as the steel would be encapsulated in resin and hopefully everything would be stuck together as well.
Well, that is my idea! Anyone care to comment?
The cost of boating is insignificant compared to costs of a young wife and two teenage kids! |
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