Iron ingot in GRP in forward bilge

[RANGERBOY]

Hello - this in my first post in YBW, so hope it's in the right place.
My 1973 GRP Contest 31 is sitting 'down' at her stern a little too much for my liking, almost certainly due all the heavy bits and pieces being distributed aft of midships. It's particularly noticeable when she's sitting on her mooring in calm conditions. To compensate, a previous owner has tried (not too successfully) to rectify this, by locating a number of 2 inch thick flat iron pieces in the forepeak bilge. They seem firmly bonded to the GRP - possibly with tar or perhaps mastic. They've been painted over with bilge paint, probably for cosmetic reasons. Any water from the chain locker dribbles onto them - there is signs of surface rust, but not heavy corrosion. Had they been encapsulated in the GRP, I would have been very concerned but as they are not encapsulated, I'm convincing myself that any rusting and consequential 'swelling' will do no harm. However, I would be interested to know if there's any known potential negative reaction between GRP and the oxidisation of iron or any other ferrous metal. Any thoughts, theories or facts will be welcomed please.

Thanks. Mike

 

[Deleted member 36384]

Mike,

Welcome to the forum. Apart from making a mess if they get rusty, as you describe the installation I don't see that there will be any issues. Many GRP yachts with encapsulated keels have iron as the ballast, sealed over with resin, bonded together with resin and with no issues provided it remains dry. I have seen lead ingots used for the same purposes as your iron but placed loosely under the saloon cabin sole, expensive option but you can always sell the lead again if you sell on the boat.

 

[Easticks28]

My yacht has an iron ballast keek bolted on to the GRP keel moulding. Never had a problem,

 

[convey]

Why not glass it over? If, big if, it was going to rust and expand all it would do is raise the thin stuff on the inside that you laid down, not try and pop out the outside. Just enough to seal it.

I saw an interesting hack recently where someone raised the sole of their chain locker to above the water line, and then drilled holes for water to escape by itself. It's an idea other boats have used straight ought of the factory. Normally, it's the kind of thing people would use to hide more floatation, but in your case you could use it to hide more ballast.

Just line uo your friend and family in order of weight and have them stand on the prow until you get the balance you want, and work out the weight.

 

[greeny]

Can't any of the weight be redistributed from aft or does it all have to be there? Moving weight would be better than adding more. I know you didn't specifically mention adding weight but if you want to sort out the trim then relocating weight is the best answer.

 

[Catalina36]

Years ago I had this discussion with my late brother who wanted to add lead shot ballast but wanted to trim the 17 foot boat level when empty. I tried to point out the effect of two or three adults in the cockpit and the benefits of bow-down when empty but to no avail so lead shot was glassed in to make it level. It dragged its rse for evermore.

SG of lead, 11+. SG of iron 7+ Lead price about £1 per kg.

 

[LONG_KEELER]

Can't any of the weight be redistributed from aft or does it all have to be there? Moving weight would be better than adding more. I know you didn't specifically mention adding weight but if you want to sort out the trim then relocating weight is the best answer.

Would be nice wouldn't it.

I'm sure that many of us have been invited for a drink or three in a boat
with four or heavy five bods in the cockpit sipping with water up to the shoe laces.

 

[RANGERBOY]

Mike,

Welcome to the forum. Apart from making a mess if they get rusty, as you describe the installation I don't see that there will be any issues. Many GRP yachts with encapsulated keels have iron as the ballast, sealed over with resin, bonded together with resin and with no issues provided it remains dry. I have seen lead ingots used for the same purposes as your iron but placed loosely under the saloon cabin sole, expensive option but you can always sell the lead again if you sell on the boat.

Thanks to everyone for their replies, but my problem is not trimming her

Hello - this in my first post in YBW, so hope it's in the right place.
My 1973 GRP Contest 31 is sitting 'down' at her stern a little too much for my liking, almost certainly due all the heavy bits and pieces being distributed aft of midships. It's particularly noticeable when she's sitting on her mooring in calm conditions. To compensate, a previous owner has tried (not too successfully) to rectify this, by locating a number of 2 inch thick flat iron pieces in the forepeak bilge. They seem firmly bonded to the GRP - possibly with tar or perhaps mastic. They've been painted over with bilge paint, probably for cosmetic reasons. Any water from the chain locker dribbles onto them - there is signs of surface rust, but not heavy corrosion. Had they been encapsulated in the GRP, I would have been very concerned but as they are not encapsulated, I'm convincing myself that any rusting and consequential 'swelling' will do no harm. However, I would be interested to know if there's any known potential negative reaction between GRP and the oxidisation of iron or any other ferrous metal. Any thoughts, theories or facts will be welcomed please.

Thanks. Mike

Thanks to all for your replies. The first part of my post was just a wee bit of background information leading to my a specific question about whether or not there is a known reaction (chemical) between GRP/resin and oxidisation. The issue of trim is of course another matter all together - I don't have a problem resolving that. BlowingOldBoots is of course absolutely right about many yachts having encapsulated iron keel and have been problem free (providing the water doesn't get in). What I was trying to say was that I'm glad that the previous owner who put in the iron pieces didn't glass them in as other jobs they'd done left a lot to be desired.

 

[Spirit (of Glenans)]

I could hazard a strong guess that iron oxide will not harm GRP on any way, but I'm open to be corrected.
In the matter of trimming, could I suggest that you ballast the forward end of the boat with plenty of anchor chain. It would be a win-win solution.
The iron pieces you describe seem to be similar to the railway fish-plates used to ballast the Heir Island Lobster Boats and other traditional boats in Baltimore as a result of the closure of the local branch line in 1965.