Maq Posted March 26, 2017 Report Share Posted March 26, 2017 Upon removal of the old gas boiler and cupboard I uncovered a serious rust issue in the corner of my narrowboat! over one mm of steel was bulging off from the body the boat. I want to scrape it back, sand it and treat the metal with red oxide or similar buitman etc what course of action is recomended? am I potentially risking to sink if I scrape it back? there was obvious overplating on the outside in this area but am really concerned. photos attached. Link to comment Share on other sites More sharing options...
bizzard Posted March 26, 2017 Report Share Posted March 26, 2017 14 minutes ago, Maq said: Upon removal of the old gas boiler and cupboard I uncovered a serious rust issue in the corner of my narrowboat! over one mm of steel was bulging off from the body the boat. I want to scrape it back, sand it and treat the metal with red oxide or similar buitman etc what course of action is recomended? am I potentially risking to sink if I scrape it back? there was obvious overplating on the outside in this area but am really concerned. photos attached. I think that is an early Harborough Marine hull. If so the swim, uxter and baseplate will be only 1/4'' or 6mm plate and the hull sides probably 4mm. Link to comment Share on other sites More sharing options...
Rickent Posted March 26, 2017 Report Share Posted March 26, 2017 Doesn't 1mm of rust equate to something like 0.1mm of actual steel? If so i don't think you are in danger of sinking. More knowledgeable peeps will be along soon to confirm or deny this. Link to comment Share on other sites More sharing options...
WotEver Posted March 26, 2017 Report Share Posted March 26, 2017 The best course of action I think would be to pay a surveyor to ultrasound check the thickness of the remaining steel, if only for your own peace of mind. Link to comment Share on other sites More sharing options...
stegra Posted March 26, 2017 Report Share Posted March 26, 2017 Scraping the rust off isn't going do any harm. Rust is doing nothing but hold the moisture in. It has no strength. Link to comment Share on other sites More sharing options...
Bee Posted March 26, 2017 Report Share Posted March 26, 2017 Actually I think that's quite bad rust, that piece of overplating in the pic is on the LHS, if it goes all round the counter to the other side and covers that area then its probably ok but I would try to have a look at the forward side of the bulkhead to make sure the rust hasn't crept through to the bit that's not overplated. If it has then a bit more plating needs to be done sharpish. If its ok there and not spread along that edge then the steel in the pic is not really doing anything, its the overplating that is structural. Personally I would leave it alone until you are sure its all safe and then chip all the bad stuff off and paint it. The thing is that the cause of this is probably rainwater pooling there and if there is a hole through the old steel then water will get to the back of the overplating and that is a Bad Thing so you need to fill that area with weld ? filler? anything black and sticky? and stop water getting at it. Link to comment Share on other sites More sharing options...
Neil2 Posted March 28, 2017 Report Share Posted March 28, 2017 Looking at those pictures I would be slightly concerned - it doesn't look like rainwater damage to me, nor does it look like the fallout from a leaky boiler. The fact that the same area has been overplated on the outside and the likelihood of this being an very old boat with relatively thin steel, I reckon that could be rusted through from the outside. If so the overplating may well have it covered but I'd be inclined to get a (boat) builder to look at it, and if the boat's in the water I wouldn't start hacking away at the rust. Link to comment Share on other sites More sharing options...
Bod Posted March 28, 2017 Report Share Posted March 28, 2017 Now it's had a chance to air a bit, is the rust damp/wet, or dry? Assuming the boat is still in the water, damp/wet, where's it coming from? Are some bits wetter? Dry, then not such a hurry to fix. Bod Link to comment Share on other sites More sharing options...
koukouvagia Posted March 28, 2017 Report Share Posted March 28, 2017 (edited) I was always a bit blasé about knocking off rust. I knew, or thought I knew the arguments, "it always looks worse than it is; 1 mm of rust equates to 0.1 mm of steel, etc." That is until I knocked a hole in the rear of our butty. I would be very careful. On investigation 70% of the back end of our butty has had to be renewed. It looked fine from the outside, but had rotted from the inside where leaks and condensation behind the lining had done their worst over the years. Edited March 28, 2017 by koukouvagia needed to an an accent on blasé Link to comment Share on other sites More sharing options...
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