Advice Sought - Removing / Grinding Horiztontal Deck Welds

[KochADV]

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.

Hi Paddy.. thanks for the detailed post. I believe (but dint know yet) they are hollow u sections.


Will start in a couple of weeks... will post updates.

Cheers!

 

[KochADV]

Paddys milestone is a viable method. But there is a lot of awkward corners there for someone not familiar with hefty grinders so lots of opportunity for kick-back and accidents. Personally I would cut down vertically as Paddy says and then get someone decent with a gas torch (Oxy acetylene)) to run along the bottom (assuming you can get access to the deckhead below for a fire-watcher). Couple of hours tops and a big saving on discs / effort. Remove all flam stuff and use wet blankets to limit spread.

Hi Blue seas... great advice. There is a shipyard in the harbour i will have a chat to them. Perhaps a day on board and they can do more than i can in a week. The boat has to come out of the water in January so that might be the best time and place to do it.

I might just remove sections now that are causing pooling of water on deck.

Cheers and thanks

Rich

 

[rogerthebodger]

Roger... my first priority is to stabilise the steel and aluminium. There is a rotting corner of the wheelhouse that needs to be fixed. And given the wheelhouse is stripped i should probably check the steel to aluminium insulation. If ur set up and ibterested to do freelance work would be good to chat. Cheers

I don't do work for others, and I am a long way from the UK and EU but can give advice either on the forum of by PM if you can send PM's

As for grinders I have several mains small angle grinders and a number several big angle grinders for various functions other than grinding I do lots of stainless polishing.

When I started in Engineering over 50 years ago, we only had 7" 9" angle grinders the 4 " one came along later.

A die grinder may be useful in tight places. When and If you get into welding, I would use a MIG setup and it reduces the slag reducing the strength of the weld and with welding practice practice and practice.

The difficulty with MIG is getting a gas bottle as here they are like hen's teeth

 

[SchoonerElinor1860]

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.

One thing about grinding is as mentioned the sparks, but you do need to contain the are from all those little sparks because if you don't check the contained area with a magnet then rust spots will appear everywhere, it's one problem with grinding, and use a small one hand grinder, use fire blankets to contain the area, they are more expensive but very useful on a metal boat,

 

[colhel]

One those questions I feel a bit cautious asking but. Are they actually welded to the deck and not just screwed down?

 

[KochADV]

I don't do work for others, and I am a long way from the UK and EU but can give advice either on the forum of by PM if you can send PM's

As for grinders I have several mains small angle grinders and a number several big angle grinders for various functions other than grinding I do lots of stainless polishing.

When I started in Engineering over 50 years ago, we only had 7" 9" angle grinders the 4 " one came along later.

A die grinder may be useful in tight places. When and If you get into welding, I would use a MIG setup and it reduces the slag reducing the strength of the weld and with welding practice practice and practice.

The difficulty with MIG is getting a gas bottle as here they are like hen's teeth

Thanks for letting me know. Might PM you with questions. Thanks!!

 

[KochADV]

One those questions I feel a bit cautious asking but. Are they actually welded to the deck and not just screwed down?

Hi Colhel... good question.. 99% sure they are welded on, but only been on board once for the pre-sale inspection. If screwed on I guess that makes life easier. Let's see...

 

[KochADV]

One thing about grinding is as mentioned the sparks, but you do need to contain the are from all those little sparks because if you don't check the contained area with a magnet then rust spots will appear everywhere, it's one problem with grinding, and use a small one hand grinder, use fire blankets to contain the area, they are more expensive but very useful on a metal boat,

Excellent point! Do you advise me to go round the contained area with a magnet to pick up all the metal particles? Makes perfect sense!! Thanks

Regarding fire blankets... are these the same as used in the kitchen? Or are there special types available for welding and grinding? Thanks

 

[DinghyMan]

Excellent point! Do you advise me to go round the contained area with a magnet to pick up all the metal particles? Makes perfect sense!! Thanks

Regarding fire blankets... are these the same as used in the kitchen? Or are there special types available for welding and grinding? Thanks

Welding fire blankets are much heavier duty than kitchen fire blankets but you can use either

Only downside is that as kitchen fire blankets are designed to be single use the edges tend to fray and drop fibres everywhere

If you have a lot of work to do, and it sounds like you do, get a proper welding fire blanket

 

[KochADV]

I would definitely try and get 110/240v tools to the job not cordless. I echo everything that's been said re fire risk, and I would really emphasise the physical discomfort of a job like this - you need big knee pads, tough overalls, long, thick leather gloves (welder's gloves are good) serious eye protection with no gaps down the sides (ie goggles not safety glasses) and proper ear protection. I'd wear earplugs inside ear defenders myself. And a really good mask, not just a casual paper mask but a chunky filter cartridge one. And some kind of hat to protect your hair too.
I think you'll end up kneeling on the deck with the tool braced against a knee, rather than just waving it about at arm's length - you can control it much better that way, especially if you go bigger in terms of disc size.

Hi MrBaxter.. thanks for this advice. Much appreciated. I have seen people reccomend a full face plastic shield AND wear goggles underneath. If a shield comes with a "hat" even better...

Thank you for the ear defender / ear plug combo... is written in my PPE prep instruction.

The only reason I want battery is for my own protection. I just hate working wtih 240 V on the water... if I drop the grinder in water it will die not me.. but point taken... and perhaps this is one I might have to "learn by doing".. lets see what happens.

Thanks again,

Rich

 

[KochADV]

Welding fire blankets are much heavier duty than kitchen fire blankets but you can use either

Only downside is that as kitchen fire blankets are designed to be single use the edges tend to fray and drop fibres everywhere

If you have a lot of work to do, and it sounds like you do, get a proper welding fire blanket

Good advice.. will invest in a proper welding blanket. Thanks!!

 

[KochADV]

Agree, bloke working for me set his tee shirt on fire with a little angle grinder.. Patted it out, but it restarted as the cloth was synthetic. Pulled it off quickly, but burned the hairs in his nose, so everything smelled of that for a bit.

Maybe the merino will come out.. I believe that is more fire retardant than cotton or synthetic (?)

 

[RivalRedwing]

all this talk of grinders, cutting wheels and local protection - do remember boats along side too, they'll not appreciate fine angle grinder debris in their topsides

 

[rogerthebodger]

I have seen people reccomend a full face plastic shield AND wear goggles underneath. If a shield comes with a "hat" even better...



Thanks again,

Rich

I use an auto darkening welding helmet like one of these

Welding Helmets Auto Darkening for sale | eBay

 

[DownWest]

Maybe the merino will come out.. I believe that is more fire retardant than cotton or synthetic (?)

Yes, the shirt I refered to was cotton polyester..
But, more important is to always make sure the sparks are 'going away' from you. I use old cotton 'sweat' tops, gauntlets and a clear mask with a hat.
I do a lot of welding and use a plane old mask for quick stuff or an autodarkening for mig and tig, but while it has a light tint for grinding and good protection, the field of vision is limited for grinding and even the light tint is too dark to see detail.

I like Roger's link, but while I know it is just for illustration, the delivery prices from the US double the price.. Not to mention some of the 'Artwork' would be a bit startling to a few of my clients Bulbous half naked dames could damage their opinion of me....

 

[PaulRainbow]

I use an auto darkening welding helmet like one of these

Welding Helmets Auto Darkening for sale | eBay

For grinding ?

 

[DownWest]

For grinding ?

Not for serious work, just the odd touch-up.

 

[PaulRainbow]

Not for serious work, just the odd touch-up.

Hmm, never used a welding mask for grinding.

 

[Rum Run]

Hi MrBaxter.. thanks for this advice. Much appreciated. I have seen people reccomend a full face plastic shield AND wear goggles underneath. If a shield comes with a "hat" even better...

Thank you for the ear defender / ear plug combo... is written in my PPE prep instruction.

The only reason I want battery is for my own protection. I just hate working wtih 240 V on the water... if I drop the grinder in water it will die not me.. but point taken... and perhaps this is one I might have to "learn by doing".. lets see what happens.

Thanks again,

Rich

If you really need to use 240VAC tools, make sure your extension lead is plugged into an RCCB, or use 110VAC kit through a 3KW or 5KW transformer (yellow box), which is the professional way here.. In the UK this kit is pretty economical, especially bought second-hand. Ebay all the way....

 

[KochADV]

If you really need to use 240VAC tools, make sure your extension lead is plugged into an RCCB, or use 110VAC kit through a 3KW or 5KW transformer (yellow box), which is the professional way here.. In the UK this kit is pretty economical, especially bought second-hand. Ebay all the way....

Thanks... will take a serious look at this.