Soft Core and Mast Step Repair
Posted: Thu Mar 03, 2022 9:43 pm
This post is long. I just spent over an hour doing it only to find that I had been timed out. I will start again but will do it in small bits and add to it. Wish me luck.
On my boat, I have bad cracks in the roof around the mast step area. This indicates a soft Core in the roof area. If that's the case, then water has been in there. Where can that come from I ask. Well, here are the possibilities.
1. The bolts holding the mast step can allow water in there if not sealed correctly.
2. The hand rails have been replaced by a previous owner. If when this was done, the old mounting holes have not been sealed, water can get in there.
3. If when fitting the new hand rails, no sealer was used to do this then water can leak in there.
4 there is an electrical plug fitted to the cabin roof just behind the mast. Water can leak in there if it is not sealed correctly.
5. Any other fitting in the roof such as the hinges for the hatch or a turning block are bolted on. If not sealed there water can also get in there.
On my boat all of the above were in fact the case. This is why I bang on about the right and wrong way of doing things on a boat.
All fittings on a boat need to be fitted by the following method.
Remove the fitting, over drill the bolt holes to double the size, use Gorilla tape ( about $30 per roll at Bunnings) on the inside and fully fill the hole with epoxy. Then drill the new mounting hole through the epoxy and re fit the fitting using a good sealer like Sikaflex. Never sylastic. A lot if work? Yes, but the more you do, the easier it is. And it is VERY WORTH WHILE.
Anyway, the core in my boat was soft as butter. There are two ways of fixing it. Cut the outer skin off, replace the core and then try to re fibreglass the skin back on again. A nightmare quite frankly.
Second method is what I did, try to determine the extent of the problem by tapping the roof with a hammer. You will hear the different sound on solid core or soft Core.
Remember that if the core is soft, then the chances are that it's also wet. This is where time comes into its own.
To inject an area, first you completely cover it with the best quality masking tape you can find. Use a measuring tape and a pencil and mark out in a square pattern where you are going to drill through the outer skin.
On mine, I did the whole roof. If it is hollow in there, you can use a compressor set to a low pressure, squirt air into one of the holes and it will blow out the others. If there is water in there, you will see it exiting. If this is the case, you need to work on it often, heat inside the boat, flush air through it often and do it over a long period of time to get it dry.
Once dry, it can be injected with epoxy.
When using epoxy for this job, I use winter hardener or slow hardener to give longer working time. Also, slow setting epoxy is stronger than fast cure.
Because the roof slopes forward and down at the sides, I made up little tapered plugs from a length of thin dowel in the lathe using a file to make it tapered. Then cut them off at about 30mm long. I made a couple of dozen of them. Using them stops the epoxy just running out of the lowest holes and then all over the cabin sides and deck. I removed them after a time before the epoxy had fully set. It needs to be non fluid to remove them but care is needed not to disturb the epoxy in the core.
I used a 60ml syringe and a small mixing cup to work easier and did a section at a time. If you are unable to get the epoxy to flow, that means that the core at that point is solid. If its hollow you will have no problem injecting. While it's taking on epoxy, keep it coming. The core needs to be full.
I mixed up about 4 pumps full of epoxy each time. Here is the tools I used
The drill size needs to be the same size that you can just get the tip of the syringe to fit it firmly.
I purchased a small set if drill stops from "Wish" on line cheap as chips and used one that fitted the drill, tightened up the grub screw so the drill just went through the top layer of gibreglass.
Once the epoxy has set, the masking tape is removed and you are left with small holes every 50mm square. I then mixed up a small amount of epoxy and thickened it with filling fairing powder to a stiff tooth paste consistency, used an epoxy stirrer stick sharpened to a blunt point to allow a small dob of filler to each hole. Where the non skid sections are, its not too important to get a perfect finish as it's rough as it is and when you paint it with the rubberised non skid paint, you won't even see it.
Where it is on smooth fibreglass, over fill the holes slightly. Once it has been sanded , undercoated with 2 pack primer and sanded and final coated you won't see any evidence of it This is mine, yet to be primed and painted
Now, to the Mast Step.
Once I knew that I had a soft Core, I also realised that the timber in the mast step would also be rotten.
I decided to cut the top out of the mast step leaving a small area of the top of it there to fibreglass on to later.
To understand the problem, I will explain the method of construction that I found out as I went deeper and deeper into it.
To make the cabin, the outer skin would be left in the mold. The core material ( plywood) put in place, a piece of around 20mm plywood shaped to fit in the top of the mast step. These materials were placed there while the fibreglass of the outer skin was still wet so it sticks there. As well as this, there is small pieces of timber placed in each of the hand rail mounts. Then one layer of fibreglass is layer over the ply of the mast step. Then it was two pieces of 2 x 1 inch timber notched out and fitted together in the shape of a cross was fitted to the mast step on the wet one layer of glass over the ply. Then the inner skin was layer up completing the cabin molding. So, we are left with four voids in each corner of the mast step on the inside in each corner of the mast step. Also we have voids around the small timbers in each of the eight hand rail mounts. These were later drilled and filled with epoxy as well as the roof core.
When I injected the roof, I worked towards the mast step and ended up injecting quite a lot of epoxy in that region ( due to the voids described earlier).
See photos below. After chiselling out the wet 20mm plywood
Here you can see the 2 x 1 cross pieces. They were removed. Here you can see the inside skin where the glass had stuck to the 2 x 1. Also note you can see some of the holes where I filled the core.
I then cut out a piece of about 5 or 6 mm marine ply to form a base from which to work. This was set in thickened epoxy to avoid getting any small voids in there. I had to use the mast step mount holes from the inside skin and gradually work them up through the ply inserts I fitted to get their location spot on. Where the bolt holes are, I bored out the holes through all pieces of ply to 1 inch, filled them with epoxy, then drilled them through the first piece from the inside. I also made an aluminium mold of the bolt holes to help me as I went. Very important to get the holes spot on otherwise the mast would end up out of alignment. Filling the bored out holes with epoxy is the only way of ensuring that water never gets back into the ply again once I started on 2nd and subsequent layers of ply, I had to cut them in half to maximise the amount of ply I could get in there. As I layer in each layer, I filled all around in there with epoxy so it eventually became one solid mass. Also, the epoxy also glued each piece together. Layer 2 Once all but 1 layers of ply were fitted, I layer up 3 layers of double biaxle woven rovings ( super strong) which was also glassed on to the inside sides of the mast step molding Last piece in place. As each layer of ply was fitted it was filled all around with epoxy Then 5 layers of the same woven rovings were glassed on and trimmed Then I used fibreglass tape to lay a fey layers over the top and down the sides of the mast step. Filled and faired ready to paint. This has been an extremely time consuming job as well as a lot of time on old knees at an awkward angle, but I can guarantee you one thing. This is now the strongest roof and mast step on any Investigator anywhere.
If you have the same problems, then don't be afraid. Anyone can do this with a little guidance. I hope I have achieved that for you.
Cheers
On my boat, I have bad cracks in the roof around the mast step area. This indicates a soft Core in the roof area. If that's the case, then water has been in there. Where can that come from I ask. Well, here are the possibilities.
1. The bolts holding the mast step can allow water in there if not sealed correctly.
2. The hand rails have been replaced by a previous owner. If when this was done, the old mounting holes have not been sealed, water can get in there.
3. If when fitting the new hand rails, no sealer was used to do this then water can leak in there.
4 there is an electrical plug fitted to the cabin roof just behind the mast. Water can leak in there if it is not sealed correctly.
5. Any other fitting in the roof such as the hinges for the hatch or a turning block are bolted on. If not sealed there water can also get in there.
On my boat all of the above were in fact the case. This is why I bang on about the right and wrong way of doing things on a boat.
All fittings on a boat need to be fitted by the following method.
Remove the fitting, over drill the bolt holes to double the size, use Gorilla tape ( about $30 per roll at Bunnings) on the inside and fully fill the hole with epoxy. Then drill the new mounting hole through the epoxy and re fit the fitting using a good sealer like Sikaflex. Never sylastic. A lot if work? Yes, but the more you do, the easier it is. And it is VERY WORTH WHILE.
Anyway, the core in my boat was soft as butter. There are two ways of fixing it. Cut the outer skin off, replace the core and then try to re fibreglass the skin back on again. A nightmare quite frankly.
Second method is what I did, try to determine the extent of the problem by tapping the roof with a hammer. You will hear the different sound on solid core or soft Core.
Remember that if the core is soft, then the chances are that it's also wet. This is where time comes into its own.
To inject an area, first you completely cover it with the best quality masking tape you can find. Use a measuring tape and a pencil and mark out in a square pattern where you are going to drill through the outer skin.
On mine, I did the whole roof. If it is hollow in there, you can use a compressor set to a low pressure, squirt air into one of the holes and it will blow out the others. If there is water in there, you will see it exiting. If this is the case, you need to work on it often, heat inside the boat, flush air through it often and do it over a long period of time to get it dry.
Once dry, it can be injected with epoxy.
When using epoxy for this job, I use winter hardener or slow hardener to give longer working time. Also, slow setting epoxy is stronger than fast cure.
Because the roof slopes forward and down at the sides, I made up little tapered plugs from a length of thin dowel in the lathe using a file to make it tapered. Then cut them off at about 30mm long. I made a couple of dozen of them. Using them stops the epoxy just running out of the lowest holes and then all over the cabin sides and deck. I removed them after a time before the epoxy had fully set. It needs to be non fluid to remove them but care is needed not to disturb the epoxy in the core.
I used a 60ml syringe and a small mixing cup to work easier and did a section at a time. If you are unable to get the epoxy to flow, that means that the core at that point is solid. If its hollow you will have no problem injecting. While it's taking on epoxy, keep it coming. The core needs to be full.
I mixed up about 4 pumps full of epoxy each time. Here is the tools I used
The drill size needs to be the same size that you can just get the tip of the syringe to fit it firmly.
I purchased a small set if drill stops from "Wish" on line cheap as chips and used one that fitted the drill, tightened up the grub screw so the drill just went through the top layer of gibreglass.
Once the epoxy has set, the masking tape is removed and you are left with small holes every 50mm square. I then mixed up a small amount of epoxy and thickened it with filling fairing powder to a stiff tooth paste consistency, used an epoxy stirrer stick sharpened to a blunt point to allow a small dob of filler to each hole. Where the non skid sections are, its not too important to get a perfect finish as it's rough as it is and when you paint it with the rubberised non skid paint, you won't even see it.
Where it is on smooth fibreglass, over fill the holes slightly. Once it has been sanded , undercoated with 2 pack primer and sanded and final coated you won't see any evidence of it This is mine, yet to be primed and painted
Now, to the Mast Step.
Once I knew that I had a soft Core, I also realised that the timber in the mast step would also be rotten.
I decided to cut the top out of the mast step leaving a small area of the top of it there to fibreglass on to later.
To understand the problem, I will explain the method of construction that I found out as I went deeper and deeper into it.
To make the cabin, the outer skin would be left in the mold. The core material ( plywood) put in place, a piece of around 20mm plywood shaped to fit in the top of the mast step. These materials were placed there while the fibreglass of the outer skin was still wet so it sticks there. As well as this, there is small pieces of timber placed in each of the hand rail mounts. Then one layer of fibreglass is layer over the ply of the mast step. Then it was two pieces of 2 x 1 inch timber notched out and fitted together in the shape of a cross was fitted to the mast step on the wet one layer of glass over the ply. Then the inner skin was layer up completing the cabin molding. So, we are left with four voids in each corner of the mast step on the inside in each corner of the mast step. Also we have voids around the small timbers in each of the eight hand rail mounts. These were later drilled and filled with epoxy as well as the roof core.
When I injected the roof, I worked towards the mast step and ended up injecting quite a lot of epoxy in that region ( due to the voids described earlier).
See photos below. After chiselling out the wet 20mm plywood
Here you can see the 2 x 1 cross pieces. They were removed. Here you can see the inside skin where the glass had stuck to the 2 x 1. Also note you can see some of the holes where I filled the core.
I then cut out a piece of about 5 or 6 mm marine ply to form a base from which to work. This was set in thickened epoxy to avoid getting any small voids in there. I had to use the mast step mount holes from the inside skin and gradually work them up through the ply inserts I fitted to get their location spot on. Where the bolt holes are, I bored out the holes through all pieces of ply to 1 inch, filled them with epoxy, then drilled them through the first piece from the inside. I also made an aluminium mold of the bolt holes to help me as I went. Very important to get the holes spot on otherwise the mast would end up out of alignment. Filling the bored out holes with epoxy is the only way of ensuring that water never gets back into the ply again once I started on 2nd and subsequent layers of ply, I had to cut them in half to maximise the amount of ply I could get in there. As I layer in each layer, I filled all around in there with epoxy so it eventually became one solid mass. Also, the epoxy also glued each piece together. Layer 2 Once all but 1 layers of ply were fitted, I layer up 3 layers of double biaxle woven rovings ( super strong) which was also glassed on to the inside sides of the mast step molding Last piece in place. As each layer of ply was fitted it was filled all around with epoxy Then 5 layers of the same woven rovings were glassed on and trimmed Then I used fibreglass tape to lay a fey layers over the top and down the sides of the mast step. Filled and faired ready to paint. This has been an extremely time consuming job as well as a lot of time on old knees at an awkward angle, but I can guarantee you one thing. This is now the strongest roof and mast step on any Investigator anywhere.
If you have the same problems, then don't be afraid. Anyone can do this with a little guidance. I hope I have achieved that for you.
Cheers