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#1
posted to rec.boats.building
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under water repair
My Draco 2500 twincab has been repowered with VW td engines and tunnel
drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? |
#2
posted to rec.boats.building
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under water repair
Perhaps your dilemma is far worse than you suspect. If you have a leak into
a foamed area and that foam is not closed cell, you have foam that will be waterlogged. If also in that same cavity you have end grain glass exposed, you will also suffer osmosis. I am afraid you have a winter project redoing the entire area. The cost of NOT doing that will be far worse. Steve "Cornelis Koger" wrote in message ... My Draco 2500 twincab has been repowered with VW td engines and tunnel drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? |
#3
posted to rec.boats.building
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under water repair
"Cornelis Koger" wrote: My Draco 2500 twincab has been repowered with VW td engines and tunnel drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? Steve Lusardi wrote: Perhaps your dilemma is far worse than you suspect. If you have a leak into a foamed area and that foam is not closed cell, you have foam that will be waterlogged. If also in that same cavity you have end grain glass exposed, you will also suffer osmosis. I am afraid you have a winter project redoing the entire area. The cost of NOT doing that will be far worse. Steve Haul out, rip out stern tube, remove waterlogged foam and dry out, grind back to sound GRP, replace the bonded in nuts. laminate up a GRP tube to sleeve the stern tube, bond in place checking alignment carefully, fair and make good. When fully cured, bed the stern tube and its end fittings in with plenty of a good quality sealant. (Assuming metal stern tube, a GRP one gets glassed in directly.) There is NO shortcut. OTOH the leak could be anywhere along the joint of the hull extension so you may have an even bigger job as if its leaking at the joint, the structural integrity of the whole addition is questionable. If foam wasn't involved you *might* have been able to bodge it with epoxy putty applied underwater. The dye isn't going to be any use as the volume of water allready in the foam will dilute it to the point that you dont get a clear colour change in anything like a reasonable time to keep the sponge in place. Been there myself and spent a winter on the hard fixing it right. |
#4
posted to rec.boats.building
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under water repair
"IanM" wrote in message ... "Cornelis Koger" wrote: My Draco 2500 twincab has been repowered with VW td engines and tunnel drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? Steve Lusardi wrote: Perhaps your dilemma is far worse than you suspect. If you have a leak into a foamed area and that foam is not closed cell, you have foam that will be waterlogged. If also in that same cavity you have end grain glass exposed, you will also suffer osmosis. I am afraid you have a winter project redoing the entire area. The cost of NOT doing that will be far worse. Steve Haul out, rip out stern tube, remove waterlogged foam and dry out, grind back to sound GRP, replace the bonded in nuts. laminate up a GRP tube to sleeve the stern tube, bond in place checking alignment carefully, fair and make good. When fully cured, bed the stern tube and its end fittings in with plenty of a good quality sealant. (Assuming metal stern tube, a GRP one gets glassed in directly.) There is NO shortcut. OTOH the leak could be anywhere along the joint of the hull extension so you may have an even bigger job as if its leaking at the joint, the structural integrity of the whole addition is questionable. If foam wasn't involved you *might* have been able to bodge it with epoxy putty applied underwater. The dye isn't going to be any use as the volume of water allready in the foam will dilute it to the point that you dont get a clear colour change in anything like a reasonable time to keep the sponge in place. Been there myself and spent a winter on the hard fixing it right. Did you write this to cheer me up? The stern tube, 2,5" diameter, has a welded on flange of 10x12", bolted to the outside of the 2" thick stern. A short 3,5" tube is welded on the inner side, laminated in the 2"stern with just glass and resin, almost flush with the inner engine bay wall. The 4 holes in the flange served the purpose of assembling and aligning the construction only. All metal parts are marine grade stainless steel. The stern tube protrudes 2 ft behind the stern, has ball bearings and tapered roller bearings to take up axial and radial forces and is oil filled. Ripping that all out really is no option! The tunnels are 15" half circles, a little over 2 ft in length, made from GRP and laminated to the stern and the extension, no leakage there. At that point of the job, I should have smeared some Sikaflex around the heads of the 4 bolts, but at the time I didn't think about it. Because the tunnel entrance was blunt and fairing impossible, I made something that could best be described as a sloped ceiling. Six layers of GRP form a warped disc, laminated to the tunnels and the boat's bottom with roving and expoxy. When that was done, I left a small gap to stick a plastic tube in and filled the cavity with a polyurethane product used for sealing sewers and wells. Over 98% closed cells, doesn't rot, but hates UV. After it hardened, I cut off the excess foam and closed the gap with epoxy/glass. Finally, I quickly gave it a coat of anti-fouling and put the boat back in the water with the next high tide. The water started coming immediately, so my guess is I overlooked a small hole in a corner or somewhere along the seam between the bottom and this "ceiling". Probably a maze in the roving that was too large for the epoxy to fill. As you know, epoxy looks quite capable of filling gaps when applied, but when it warms up during curing, it is thin as water. This concerns the starboard tunnel, the port one, with identical construction, does not leak. |
#5
posted to rec.boats.building
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under water repair
Cornelis Koger wrote:
"IanM" wrote in message ... "Cornelis Koger" wrote: My Draco 2500 twincab has been repowered with VW td engines and tunnel drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? Steve Lusardi wrote: Perhaps your dilemma is far worse than you suspect. If you have a leak into a foamed area and that foam is not closed cell, you have foam that will be waterlogged. If also in that same cavity you have end grain glass exposed, you will also suffer osmosis. I am afraid you have a winter project redoing the entire area. The cost of NOT doing that will be far worse. Steve Haul out, rip out stern tube, remove waterlogged foam and dry out, grind back to sound GRP, replace the bonded in nuts. laminate up a GRP tube to sleeve the stern tube, bond in place checking alignment carefully, fair and make good. When fully cured, bed the stern tube and its end fittings in with plenty of a good quality sealant. (Assuming metal stern tube, a GRP one gets glassed in directly.) There is NO shortcut. OTOH the leak could be anywhere along the joint of the hull extension so you may have an even bigger job as if its leaking at the joint, the structural integrity of the whole addition is questionable. If foam wasn't involved you *might* have been able to bodge it with epoxy putty applied underwater. The dye isn't going to be any use as the volume of water allready in the foam will dilute it to the point that you dont get a clear colour change in anything like a reasonable time to keep the sponge in place. Been there myself and spent a winter on the hard fixing it right. Did you write this to cheer me up? The stern tube, 2,5" diameter, has a welded on flange of 10x12", bolted to the outside of the 2" thick stern. A short 3,5" tube is welded on the inner side, laminated in the 2"stern with just glass and resin, almost flush with the inner engine bay wall. The 4 holes in the flange served the purpose of assembling and aligning the construction only. All metal parts are marine grade stainless steel. The stern tube protrudes 2 ft behind the stern, has ball bearings and tapered roller bearings to take up axial and radial forces and is oil filled. Ripping that all out really is no option! The tunnels are 15" half circles, a little over 2 ft in length, made from GRP and laminated to the stern and the extension, no leakage there. At that point of the job, I should have smeared some Sikaflex around the heads of the 4 bolts, but at the time I didn't think about it. Because the tunnel entrance was blunt and fairing impossible, I made something that could best be described as a sloped ceiling. Six layers of GRP form a warped disc, laminated to the tunnels and the boat's bottom with roving and expoxy. When that was done, I left a small gap to stick a plastic tube in and filled the cavity with a polyurethane product used for sealing sewers and wells. Over 98% closed cells, doesn't rot, but hates UV. After it hardened, I cut off the excess foam and closed the gap with epoxy/glass. Finally, I quickly gave it a coat of anti-fouling and put the boat back in the water with the next high tide. The water started coming immediately, so my guess is I overlooked a small hole in a corner or somewhere along the seam between the bottom and this "ceiling". Probably a maze in the roving that was too large for the epoxy to fill. As you know, epoxy looks quite capable of filling gaps when applied, but when it warms up during curing, it is thin as water. This concerns the starboard tunnel, the port one, with identical construction, does not leak. Haul out *IN PERSON*, wipe down and look for drips (dont let the yard pressure wash). If you get lucky you *might* find the gap. Otherwise drill into the cavity and apply air at a pressure of no more than 6" water gauge, and wet all suspect areas with a 1/3 solution of dish detergent in water and look for bubbles. You've then got the problem of drying out the foam. If the leak *IS* round the stern tube, it will almost certainly have to come out. I would never trust a directly glassed in metal stern tube as unless there is a resiliant sealent between the GRP and the metal, thermal shock alone can break the bond, let alone shaft vibration. You haven't left youself any maintenance options with a one piece welded up stern tube and flange directly glassed in :-( Ideally one should be able to pull all bearings etc. from the stern tube and heat it up to break the bond and remove it non-destructively for repairs etc. Some light cleanup of the GRP shell round it and some fresh sealent and it would all go back together sweetly. Bit late for that now though. I hope for your sake the leak is elsewhere. |
#6
posted to rec.boats.building
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under water repair
"IanM" wrote in message ... Cornelis Koger wrote: "IanM" wrote in message ... "Cornelis Koger" wrote: My Draco 2500 twincab has been repowered with VW td engines and tunnel drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? Steve Lusardi wrote: Perhaps your dilemma is far worse than you suspect. If you have a leak into a foamed area and that foam is not closed cell, you have foam that will be waterlogged. If also in that same cavity you have end grain glass exposed, you will also suffer osmosis. I am afraid you have a winter project redoing the entire area. The cost of NOT doing that will be far worse. Steve Haul out, rip out stern tube, remove waterlogged foam and dry out, grind back to sound GRP, replace the bonded in nuts. laminate up a GRP tube to sleeve the stern tube, bond in place checking alignment carefully, fair and make good. When fully cured, bed the stern tube and its end fittings in with plenty of a good quality sealant. (Assuming metal stern tube, a GRP one gets glassed in directly.) There is NO shortcut. OTOH the leak could be anywhere along the joint of the hull extension so you may have an even bigger job as if its leaking at the joint, the structural integrity of the whole addition is questionable. If foam wasn't involved you *might* have been able to bodge it with epoxy putty applied underwater. The dye isn't going to be any use as the volume of water allready in the foam will dilute it to the point that you dont get a clear colour change in anything like a reasonable time to keep the sponge in place. Been there myself and spent a winter on the hard fixing it right. Did you write this to cheer me up? The stern tube, 2,5" diameter, has a welded on flange of 10x12", bolted to the outside of the 2" thick stern. A short 3,5" tube is welded on the inner side, laminated in the 2"stern with just glass and resin, almost flush with the inner engine bay wall. The 4 holes in the flange served the purpose of assembling and aligning the construction only. All metal parts are marine grade stainless steel. The stern tube protrudes 2 ft behind the stern, has ball bearings and tapered roller bearings to take up axial and radial forces and is oil filled. Ripping that all out really is no option! The tunnels are 15" half circles, a little over 2 ft in length, made from GRP and laminated to the stern and the extension, no leakage there. At that point of the job, I should have smeared some Sikaflex around the heads of the 4 bolts, but at the time I didn't think about it. Because the tunnel entrance was blunt and fairing impossible, I made something that could best be described as a sloped ceiling. Six layers of GRP form a warped disc, laminated to the tunnels and the boat's bottom with roving and expoxy. When that was done, I left a small gap to stick a plastic tube in and filled the cavity with a polyurethane product used for sealing sewers and wells. Over 98% closed cells, doesn't rot, but hates UV. After it hardened, I cut off the excess foam and closed the gap with epoxy/glass. Finally, I quickly gave it a coat of anti-fouling and put the boat back in the water with the next high tide. The water started coming immediately, so my guess is I overlooked a small hole in a corner or somewhere along the seam between the bottom and this "ceiling". Probably a maze in the roving that was too large for the epoxy to fill. As you know, epoxy looks quite capable of filling gaps when applied, but when it warms up during curing, it is thin as water. This concerns the starboard tunnel, the port one, with identical construction, does not leak. Haul out *IN PERSON*, wipe down and look for drips (dont let the yard pressure wash). If you get lucky you *might* find the gap. Otherwise drill into the cavity and apply air at a pressure of no more than 6" water gauge, and wet all suspect areas with a 1/3 solution of dish detergent in water and look for bubbles. You've then got the problem of drying out the foam. If the leak *IS* round the stern tube, it will almost certainly have to come out. I would never trust a directly glassed in metal stern tube as unless there is a resiliant sealent between the GRP and the metal, thermal shock alone can break the bond, let alone shaft vibration. You haven't left youself any maintenance options with a one piece welded up stern tube and flange directly glassed in :-( Ideally one should be able to pull all bearings etc. from the stern tube and heat it up to break the bond and remove it non-destructively for repairs etc. Some light cleanup of the GRP shell round it and some fresh sealent and it would all go back together sweetly. Bit late for that now though. I hope for your sake the leak is elsewhere. Thanks for your advice, I'll post my findings later. I did think about maintenance when I designed this, but I expected possible problems to be inside the tube, not around it. There are removable covers at both ends of it to renew oil seals or bearings in case a seal would fail and water has entered the tube. |
#7
posted to rec.boats.building
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under water repair
On Dec 7, 3:14*am, "Cornelis Koger" wrote:
My Draco 2500 twincab has been repowered with VW td engines and tunnel drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? Splash-Zone |
#8
posted to rec.boats.building
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under water repair
tomdownard wrote:
On Dec 7, 3:14 am, "Cornelis Koger" wrote: My Draco 2500 twincab has been repowered with VW td engines and tunnel drives of my own design, for which I have added a 1 ft long box to the stern. In fact it is an extension of the hull that supports the 2 tunnels, rudders etc. Although I've spent many hours on my back under the hull laminating and painting, now that the boat is back in the water, a steady trickle of water is entering the bilge through one of the holes where the stern tube is bolted to the stern. The bolts are not visible outside, they are in a grp walled cavity filled with polyurethane foam. I would have bet anything that the construction is watertight, but I'm glad I didn't. My plan is to locate the hole by pressing a sponge soaked in dye against the suspected area, with a helper inside who looks for a color change of the incoming water. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? there are lots of epoxies that can be applied underwater and will cure underwater. Lots get sold to owners of leaking swimming pools (cannot drain 30,000 gallons of water to fix a small leak) as well as to offshore sailors (I've saved at least one world cruiser that way). You can even do a fiberglass cloth/epoxy repair underwater. Leaks are often fixed with underwater epoxy soaked spong rubber - cram in the void, the sprong rubber swells up, filling the void while the epoxy does the sealing. You can certainly have these it for under $50 total. Easy to fix from the outside when water pressure is pushing everything into the hole. Much much harder to fix from the inside when water pressure is pushing the uncured epoxy out of the way. Email me for more info (disclosure - I own an epoxy company) -- |
#9
posted to rec.boats.building
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under water repair
3M 5200 I am suprised nobody has mentioned it.
Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? Den 48ft Yachtfisher EAGLE http://www.densnet.com |
#10
posted to rec.boats.building
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under water repair
3M 5200 is NOT a sealant. It is an extremely strong, flexible bonding agent.
Steve "den" wrote in message ... 3M 5200 I am suprised nobody has mentioned it. Is anyone familiar with a product or procedure that can successfully seal a small hole in a submerged object? Den 48ft Yachtfisher EAGLE http://www.densnet.com |
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