cast iron keel prep

[mbay]

Hello all,

I going to take off the surface rust on my iron keels what in your opinion is the most cost effective way of doing this?

Previously I have used a Perago blaster drill attachment which worked really well and has a similar finish to a needle gun (so i was told), the perago is not cheap though and the tungsten teeth on mine are now worn out are there any other alternatives out there?

Thanks'

 

[PeteCooper]

I'm going to use a needle scaler - I looked in to buying one but I can hire one for a weekend for I think £43 so that's what I'll do. I will hire from HSS - if you book in the shop it costs £63, if you book on-line and then go and collect it costs £43.

 

[vyv_cox]

Needle gun is reckoned to be next best after grit blasting. Used on offshore platforms in areas where blasting is not possible.

 

[mbay]

Pity i was'nt near you Pete, I'm being quoted an online price of £63.25.

How effective are these needle guns? how long should it take to do my two keels on a Westerly Pageant? just trying to weigh up wether or not to hire a gun or buy a new Perago.

I've just noticed that when you add to basket from the hss site it then applies the discount so it is £43 for the weekend hire.

also Pete i've just found this site for half the price of HSS http://www.nationaltoolhireshops.co.uk/product/needle-gun-electric-breaker-for-hire

 

[PeteCooper]

Pity i was'nt near you Pete, I'm being quoted an online price of £63.25.

I think that the £20 off doesn't appear until you actually go into the booking screen.

 

[forelle541]

I have a needle gun and tried it on the cast iron keel of my Sadler. It did not work all that well, I think that cast iron, well the soft sort in my keel will not let the needles ping off the paint like they do on steel. I went back to a flat wire brush on a grinder.

 

[vyv_cox]

A wire brush is not recommended for cast iron because it tends to drive rust and other deposits into the metal, where they inhibit corrosion protection. I prefer an angle grinder that removes all deposits and leaves a clean, bright surface.

 

[ghostlymoron]

Problem with angle grinder on my keels is that it doesn't get into the mini craters that exist in the cast iron.

 

[vyv_cox]

Problem with angle grinder on my keels is that it doesn't get into the mini craters that exist in the cast iron.

But neither would a wire brush. Which is why grit blasting is preferred above everything else, followed by needle gunning. Both have the ability to penetrate into pits.

 

[mbay]

I may be to get the keels blasted, what size grit is recommended? will soda do the job or will it have to be grit?

Also the friend that's going to do the job for me has read that its better to do it with the keels off ......obviously that's not going to happen what precautions should we take to stop the grit damaging the gelcoat?

Thanks'

 

[Rigger Mortice]

I have a needle gun and tried it on the cast iron keel of my Sadler. It did not work all that well, I think that cast iron, well the soft sort in my keel will not let the needles ping off the paint like they do on steel. I went back to a flat wire brush on a grinder.

That's what I found too. The needle gun was a waste of time and money.

 

[ghostlymoron]

I may be to get the keels blasted, what size grit is recommended? will soda do the job or will it have to be grit?

Also the friend that's going to do the job for me has read that its better to do it with the keels off ......obviously that's not going to happen what precautions should we take to stop the grit damaging the gelcoat?

Thanks'

If you grit blast it, it's essential to prime it within a few minutes otherwise flash rusting will occur and you'll have wasted your efforts. Don't know about protecting GRP, sorry.

 

[oldsaltoz]

I may be to get the keels blasted, what size grit is recommended? will soda do the job or will it have to be grit?

Also the friend that's going to do the job for me has read that its better to do it with the keels off ......obviously that's not going to happen what precautions should we take to stop the grit damaging the gelcoat?

Thanks'

The operator will select the grit type depending on the condition of the keels, Protection of areas other than the keels is a simple sheet of metal the operator holds in one hand and moves it as blating is done.

You are looking for a class class 2 and a half finish (silver frey with no shadows.

Cast iron will start rusting in minutes, so get some cover on as soon as possible. (a roller on a stick works for me) done when still blasting.

Good luck and fair winds.

 

[mbay]

Thank you oldsaltoz, the operator does not know what size grit to get, the equipment he use's is for a small side business he has running doing a bit fabrication and has never done any work outside his own garage, he asked me to try and find out the size of grit needed and aready has plenty of soda already for use but is unsure if this is corse enough?

 

[oldsaltoz]

I would be looking for a blaster with experiance, faster, better and possibly cheaper as most charge by the hour plus grit used.

Good luck and fair winds.

 

[mbay]

i sail on a very tight budget Oldsaltoz, you can't get cheaper than free

 

[oldsaltoz]

I can't argue with that.

 

[KAL]

If you grit blast it, it's essential to prime it within a few minutes otherwise flash rusting will occur and you'll have wasted your efforts. Don't know about protecting GRP, sorry.

How about using fernox on the clean iron?

 

[Searush]

I've just posted this on the other thread, why can't you guys get your act together & stop repeating threads!!! Below is my experience of hiring a needle gun from HSS.

I hired one for the keels on SR (a Pentland in case anyone has forgotten ) It was electric & came with a big transformer(?). I had wanted an oblong brush style one, but they only had a needle gun, which looks like a big drill with about an inch diam head of needles. Because of the small area, it takes a long time to cover the side of a keel, but you can lean on it to apply extra pressure in the bad places. I did all 4 keel sides in a day (9.30-4.00) including hire & return.

Obviously you need goggles, & gloves help reduce the vibration. It removed all the loose flakes very well & even broke thro into a couple of small voids in the casting (2-4mm irregular bubbles in effect) but didn't produce the bright metal finish I was expecting. The end result was an irregular pock marked rusty coloured surface with some areas almost polished. I filled the voids with epoxy & gave it a couple of cots of Primocon, then "red lead" (yup, that's what it was sold to me as, but I doubt that it was) followed by a singe coat of a/f.

The final result looked OK but not quite as smooth as a babies bum, I really laid the paints on thick on the rough areas & that filled some of the pock marks, but I wasn't interested in fairing the keels with resin filler & sanding anyway. Now, about 4 years later, it's still OK with just an odd small bit of rust showing thro in a couple of spots. If I was going to a/f this year it would cover them up again, but this year I will only be scraping them clean on a nice beach somewhere in the summer sun.

Bear in mind that this is a 1973 yacht.

part- Finished keel (unpainted), area to right has been "needled", area to left is untreated in any way;

Needle gun;

Before I started.

 

[mbay]

I've just posted this on the other thread, why can't you guys get your act together & stop repeating threads!!! Below is my experience of hiring a needle gun from HSS.

thanks for repeating this i love reading things twice