Advice Sought - Removing / Grinding Horiztontal Deck Welds

[KochADV]

Hi.. first time poster, so if I am breaking etiquette or posting in the wrong space please advise.

I have just purchased an ex-Pilot Boat and the owner had plans to replace the wheelhouse. They started work by welding the outline of the new wheelhouse around the old one. In the attached photo you can see the white rail around the deckhouse (apologies for the low resolution shot.. will be on board in a week or two and can get a better pic).

One of my first jobs will be to remove this railing as I want to maintain the classic character of the ship.

I have no experience grinding and removing welds and I would like some advice so I don't injure myself or my boat.

My questions are:
- is it feasible to grind out the welds horizontal to the deck?
- is it a 2 step process where a) the weld is cut a few millimetres above the deck and then b) ground down to deck level?
- is this the wrong approach and I should be doing something different?
- the deckhouse is alumnimum and I assume I should protect it from the grinding sparks... hope this is a no-brainer question, but would rather ask dumb questions than get it wrong.
- any advice on tool or wheel? I don't know the steel type yet and I was thinking about a battery operated model.

That should be enough for now as there is already alot here.

Thanks in advance for your help.

Richard

 

[Rum Run]

You might be better off in the Practical Boat Owner forum really.
However, the info you give seems a bit meagre for anyone to be sure precisely what you are facing so advice as to process will be suspect. Better pics and description will help.
General points though: battery power tools are unlikely to be enough for the prolonged use they will get on this job. I'd be thinking of a 9" and a 4.5" grinder with both cutting and grinding discs for both. Professionals would use 110v kit and a minimum 5kw transformer. All that can be quite cheap second hand tbh.
Protection of everything around the working area will be absolutely essential. Sparks from grinding set fire to all sorts of things - wood, clothes, paint, plastic....... Also embed in glass and aluminium. You will also need fire extinguishers and some water easily available just to damp stuff down when you get just a little fire. Which you probably will!
Oh yeah, wear knee-pads too.

 

[KochADV]

You might be better off in the Practical Boat Owner forum really.
However, the info you give seems a bit meagre for anyone to be sure precisely what you are facing so advice as to process will be suspect. Better pics and description will help.
General points though: battery power tools are unlikely to be enough for the prolonged use they will get on this job. I'd be thinking of a 9" and a 4.5" grinder with both cutting and grinding discs for both. Professionals would use 110v kit and a minimum 5kw transformer. All that can be quite cheap second hand tbh.
Protection of everything around the working area will be absolutely essential. Sparks from grinding set fire to all sorts of things - wood, clothes, paint, plastic....... Also embed in glass and aluminium. You will also need fire extinguishers and some water easily available just to damp stuff down when you get just a little fire. Which you probably will!
Oh yeah, wear knee-pads too.

Hi Rum Run.. thanks for your reply. All advice noted and very helpful.

I will also take your advice about the practical boat owners forum and move the post there.

Again.. many thanks.. especially about knee-pads! Didn't cross my mind

 

[DinghyMan]

Hi.. first time poster, so if I am breaking etiquette or posting in the wrong space please advise.

I have just purchased an ex-Pilot Boat and the owner had plans to replace the wheelhouse. They started work by welding the outline of the new wheelhouse around the old one. In the attached photo you can see the white rail around the deckhouse (apologies for the low resolution shot.. will be on board in a week or two and can get a better pic).

One of my first jobs will be to remove this railing as I want to maintain the classic character of the ship.

I have no experience grinding and removing welds and I would like some advice so I don't injure myself or my boat.

My questions are:
- is it feasible to grind out the welds horizontal to the deck?
- is it a 2 step process where a) the weld is cut a few millimetres above the deck and then b) ground down to deck level?
- is this the wrong approach and I should be doing something different?
- the deckhouse is alumnimum and I assume I should protect it from the grinding sparks... hope this is a no-brainer question, but would rather ask dumb questions than get it wrong.
- any advice on tool or wheel? I don't know the steel type yet and I was thinking about a battery operated model.

That should be enough for now as there is already alot here.

Thanks in advance for your help.

Richard

Yes, perfectly feasible to grind the welds flat, its what most welders do all day long
Yes, two step is probably easier
No, sounds like a sensible approach, other option could be get a cheap Plasma cutter but then you also need a compressor
Yes, get a welding blanket or cheaper option is a fire blanket
Tools: If you havent used one before stick with the smaller 115/125mm grinders, big ones are great but can be a bit of a beast to handle until you get used to them, and access is better with the smaller ones, battery operated is OK if you buy into a particular tool range and get a good few batteries, mains is better if available - we use Ryobi battery powered tools all day long in and out of the workshop but angle grinders will eat batteries very fast, even the big ones
Both DeWalt and Milwaukee make flat head angle grinders which are great for restricted access, but pricey
Get decent quality grinding discs and flap wheel discs, ceramic / zirconia ones, the best discs are probably 3M Cubitron which are expensive but remove metal at a fair old rate and get some Norton Blaze Rapid Strip discs for finishing / polishing where the weld was
Dont forget decent PPE - proper mask, googles, gloves, and as above - knee pads

 

[Forum Admin Team]

Threads merged.

 

[Seastoke]

Do want to cut at the bottom then lift the wheelhouse off with a crane, or are you cutting in sections. Is the boat on the water. With you being so close to other boats you need to inform the owners of your intentions as one spark off grinding on fibreglass will mark it .

 

[rogerthebodger]

Having steel boat, I do and have done quite a lot of welding both above the waterline, deck and below the waterline.

The trick to grinding weld on deck and above the water line is to bevel the join and fill the bevel in with the weld so that when grinding flush there is still plenty of weld and penetration.

Below the waterline you should NOT grind the weld flush to improve the strength of the weld.

If you ae attaching aluminum to the steel deck you MUST isolate the aluminum from the steel by using an insulation material like a plastic gasket and coat the fixing screws with Durlak as I used when fixing stainless teel to my aluminum mast

 

[PaulRainbow]

Do want to cut at the bottom then lift the wheelhouse off with a crane, or are you cutting in sections. Is the boat on the water. With you being so close to other boats you need to inform the owners of your intentions as one spark off grinding on fibreglass will mark it .

He doesn't want to remove the wheelhouse.

 

[PaulRainbow]

Having steel boat, I do and have done quite a lot of welding both above the waterline, deck and below the waterline.

The trick to grinding weld on deck and above the water line is to bevel the join and fill the bevel in with the weld so that when grinding flush there is still plenty of weld and penetration.

Below the waterline you should NOT grind the weld flush to improve the strength of the weld.

If you ae attaching aluminum to the steel deck you MUST isolate the aluminum from the steel by using an insulation material like a plastic gasket and coat the fixing screws with Durlak as I used when fixing stainless teel to my aluminum mast

He's not grinding structural welds Roger, just removing some unwanted steel that the previous owner welded in place and getting rid of the welds, restoring the deck to it's original state.

 

[Wansworth]

If your going to be using the vessel in rough weather any hand holds will be very welcome

 

[PaulRainbow]

If your going to be using the vessel in rough weather any hand holds will be very welcome

He's talking about the white metal around the wheelhouse, on the deck.

 

[Seastoke]

He's talking about the white metal around the wheelhouse, on the deck.

Oops I missed. That bit. If he reads this he will need steel wedges.

 

[thinwater]

Good advice. But there look to be about 100 things that I would do first.

And don't forget hearing protection. Very loud.

 

[Wansworth]

He's talking about the white metal around the wheelhouse, on the deck.

Ok

 

[zoidberg]

"Hi.. first time poster, so if I am breaking etiquette or posting in the wrong space please advise."

Hello, KochADV.... and welcome.

Let me wish you well with your new 'project'.

 

[rogerthebodger]

He's not grinding structural welds Roger, just removing some unwanted steel that the previous owner welded in place and getting rid of the welds, restoring the deck to it's original state.

Paul the deck is struct rial and any butt joints that are welded the ground down can crack and break apart and allow water and runt in and penetrate weaking the whole structure.

So, any welding that the OP wished to grind flush MUST be prepared correctly else problems will come back to bite him down the road.

One of the issues is always ensuring any coating (paint) that is not a flexible are the steel an crack and allow water and rust to get to the steel underneath.

It's a comprises in having the steel rigid enough to prevent flexing but light enough not to have weight too high effecting stability.

Paul all I am doing is giving my experience of having and maintaining a steel boat for many years.

Most nonskilled welders leave rough welds that do require grinding smooth for cosmetic reasons but in doing so an reduce the strength of the metal joint.

 

[PaulRainbow]

Paul the deck is struct rial and any butt joints that are welded the ground down can crack and break apart and allow water and runt in and penetrate weaking the whole structure.

There are no butt joints in the OPs question.

Someone has welded some metal on deck and he wants to remove it and grind flush the welds that were holding it in place.

So, any welding that the OP wished to grind flush MUST be prepared correctly else problems will come back to bite him down the road.

One of the issues is always ensuring any coating (paint) that is not a flexible are the steel an crack and allow water and rust to get to the steel underneath.

It's a comprises in having the steel rigid enough to prevent flexing but light enough not to have weight too high effecting stability.

Paul all I am doing is giving my experience of having and maintaining a steel boat for many years.

I don't doubt your experience of having and maintaining a steel boat Roger, but you've not understood what the OP is wanting to do.

You also say "If you are attaching aluminum to the steel deck".... he isn't, the aluminium wheelhouse is already there, an original part of the boat.

Most nonskilled welders leave rough welds that do require grinding smooth for cosmetic reasons but in doing so an reduce the strength of the metal joint.

Even a skilled welder cannot make invisible welds. If the methods you posted previously are followed strength can be maintained. FYI, i was taught to stick weld 50 years ago, followed by gas, mig, tig and brazing.

 

[rogerthebodger]

There are no butt joints in the OPs question.

Someone has welded some metal on deck and he wants to remove it and grand fluch the welds that were holding it in place.



I don't don't your experience of having and maintaining a steel boat Roger, but you've not understood what the OP is wanting to do.

You also say "If you are attaching aluminum to the steel deck".... he isn't, the aluminium wheelhouse is already there, an original part of the boat.

Even a skilled welder cannot make invisible welds. If the methods you posted previously are followed strength can be maintained. FYI, i was taught to stick weld 50 years ago, followed by gas, mig, tig and brazing.

Can I not give a new poster my experience in fabrication of steel structures over many years as you do with your claimed experience

I was taught stick and gas welding longer than you claim but it's not me or you are doing the welding it an unknown previous owner.

I currently have my own MIG and TIG welding kit in by workshop and al I no longer need to work to earn money I fiddle in my workshop and garage with boat and my classic cars o have plenty of time for make all kinds of fittings and equipment for boats and classic cars

The question really is why you are raising issues with my posts all the time you are you hoping to intimidate me to stop posting.

I have seen many knowledgeable members stop posting for this kind of comments. It's just unnecessary bickering and not productive

 

[Paddys milestone]

Looking at the photos ,it would appear that the rail is not solid but probably a U section. I am guessing this by the holes drilled in the top of the rails.
Hope for your sake that this is the case, as it will make the job a lot easier.

Surprisingly no one has suggested hiring a hefty angle grinder , at least a 150 mm wheel size. which will be big enough for the job and relatively easy to handle. Firstly I would cut vertically down the cross section of the rails to divide them into sections, about 400 long and then cut along the bottom of the outside face,as close to the deck as practical. Then cut along the back face but not all the way through, you might then be able to lever each length off ,(saves a lot of work.)
Then swap your cutting disc for a coarse grinding disc, and clean up the remaining welds, finish off with a finer disc .
Be very aware of safety ,, don't take chances wear proper gear .
Get plenty discs from the hire place, normally they will only charge you for what you use.
I have done this type of work very often ... don't envy you!


Awaiting incoming.

 

[PaulRainbow]

Can I not give a new poster my experience in fabrication of steel structures over many years as you do with your claimed experience

I was taught stick and gas welding longer than you claim but it's not me or you are doing the welding it an unknown previous owner.

Still not reading the original post. NO ONE IS DOING ANY WELDING

He's just removing a piece of metal.

Why don't you read what the OP is doing ?