Cutting Holes in Boats

[Tonyl]

Hi all, hope you are all well and enjoying the weather out there.

 

Another question , how does one go about cutting a hole in the roof or the cabin side of a narrowboat for say a vent or the like (say 75 - 150 mm diameter) ?. I base the question on being a DIY person and not having access to fancy Oxy Acet cutting geargear. Is it best left alone ?

 

Thanks

 

Tony

[zenataomm]

Hi all, hope you are all well and enjoying the weather out there.

 

Another question , how does one go about cutting a hole in the roof or the cabin side of a narrowboat for say a vent or the like (say 75 - 150 mm diameter) ?. I base the question on being a DIY person and not having access to fancy Oxy Acet cutting geargear. Is it best left alone ?

 

Thanks

 

Tony

Hi Tony ..........

 

I'd suggest you leave Oxy Acetylne well alone unless you wanted to set fire to the ceiling lining and associated batoning etc that will be in the firing line.

 

Any half decent electric jigsaw with the right blade should do the trick, just be careful you don't chop through any electric wiring, you'd be surprised where they tuck it.

[denboy]

hole saws are available as well

[Windjammer]

Get a decent holesaw such as a cobalt and use cutting paste on 4-6mm steel.

Edited May 9, 2008 by Windjammer

[Greybeard]

Hi.

 

Not a silly question at all.

 

Amongst other things I drill holes for a living............how about that for a weird job!!!!!!!!!!

 

There's all kinds of tools to cut this sized hole BUT the most important thing to remember is that if you use a drill watch out for your wrists.

 

It only takes a blink for the drill bit to jam.

[blackrose]

I am an afficionardo of the jigsaw. Mark out the hole (trying to avoid any steel supports), drill a number of 6mm holes around the circumference, put your metal cutting jigsaw blade into one of the holes and join the dots! Spray a bit of WD40 on the blade from time to time to act as a coolant.

[Greybeard]

I am an afficionardo of the jigsaw. Mark out the hole (trying to avoid any steel supports), drill a number of 6mm holes around the circumference, put your metal cutting jigsaw blade into one of the holes and join the dots! Spray a bit of WD40 on the blade from time to time to act as a coolant.

 

Job application in the post.

 

Wages are rubbish though but you can sell any holes that are left over at the end of each shift!

[denboy]

ive got a city and guilds for diggin holes

[Dylan]

I am an afficionardo of the jigsaw. Mark out the hole (trying to avoid any steel supports), drill a number of 6mm holes around the circumference, put your metal cutting jigsaw blade into one of the holes and join the dots! Spray a bit of WD40 on the blade from time to time to act as a coolant.

Exactly how I do the job. Dormer or Presto drlls (the best) and quality metal jigsaw blades, not the ones from Poundland. I hate holecutters above 75mm, for which you need an extremely slow drilling machine. Most hand held electric drills are unsuitable.

[Greybeard]

ive got a city and guilds for diggin holes

 

 

Sorry no managerial positions available.

[Machpoint005]

Job application in the post.

 

Wages are rubbish though but you can sell any holes that are left over at the end of each shift!

Did you know that a hole in a sheet of steel expands in exactly the same way as the steel that used to be there?

 

...so if you cut the same hole in a sheet of aluminium, the thermal expansion of the hole is different!

 

(I'm a mine of useless information)

[Keeping Up]

Did you know that a hole in a sheet of steel expands in exactly the same way as the steel that used to be there?

 

...so if you cut the same hole in a sheet of aluminium, the thermal expansion of the hole is different!

Does that mean that if you cut an aluminium hole in a sheet of steel, it would close up when the sun shines on it? Hey, we've just invented the automatic sunshade!

[Greybeard]

Exactly how I do the job. Dormer or Presto drlls (the best) and quality metal jigsaw blades, not the ones from Poundland. I hate holecutters above 75mm, for which you need an extremely slow drilling machine. Most hand held electric drills are unsuitable.

 

Blackrose's method is spot on and will do the job.

 

Best off going to a tool shop and buying a decent cobalt bit.

 

I was drilling 6.5mm holes through 6mm steel plate in about 10-15 seconds with a cobalt bit.

 

A standard bit will take for ever.

 

Don't get conned into buying 'diamond tipped bits' they won't do the job.

 

Did you know that a hole in a sheet of steel expands in exactly the same way as the steel that used to be there?

 

...so if you cut the same hole in a sheet of aluminium, the thermal expansion of the hole is different!

 

(I'm a mine of useless information)

 

Didn't know that but I have seen concrete expand on a sunny day..............quite violently actually!

[Machpoint005]

Does that mean that if you cut an aluminium hole in a sheet of steel, it would close up when the sun shines on it? Hey, we've just invented the automatic sunshade!

No - it will get bigger (aluminium about twice the expansion of steel). The hole expands, it doesn't get smaller. See my post above!

[Windjammer]

aluminium hole in a sheet of steel ?

 

Is that a left handed or right handed hole ?

[Timleech]

Blackrose's method is spot on and will do the job.

 

Best off going to a tool shop and buying a decent cobalt bit.

 

I was drilling 6.5mm holes through 6mm steel plate in about 10-15 seconds with a cobalt bit.

 

A standard bit will take for ever.

 

Don't get conned into buying 'diamond tipped bits' they won't do the job.

 

Doesn't need to be a cobalt drill ('cobalt' here is a particular form of High Speed Steel), just a good quality,sharp, High Speed Steel drill from the likes of Dormer, Presto, Guhring, will do just fine. Some of the cheaper brands are OK too, such as Hertel from J&L industrial, but there is an awful lot of rubbish out there.

Use lubricant on the drill as well as the holesaw or jigsaw.

If you have access to the reverse side of the plate, some lubricant smeared on here will get drawn into the cut by the jigsaw blade.

 

Tim

[DHutch]

There are other very simular threads about, such as how to cut a 5inch hole in the roof for a stove chimey. Although the answers are simular

- For one hole, i would jigsaw it, if doing lots buy a hole saw, if you dont have a jigsaw, chain drill it (lots of small holes in a line) and knock together with a chisal an file smooth. Or buy a jigsaw!

 

 

Daniel

[Greybeard]

There are other very simular threads about, such as how to cut a 5inch hole in the roof for a stove chimey. Although the answers are simular

- For one hole, i would jigsaw it, if doing lots buy a hole saw, if you dont have a jigsaw, chain drill it (lots of small holes in a line) and knock together with a chisal an file smooth. Or buy a jigsaw!

 

 

Daniel

 

I can't argue with you at all on your techniques.

 

We use the same, but call it stitch drilling, for anything over 1200mm diameter through reinforced concrete.

[ChrisPy]

Is that a left handed or right handed hole ?

depends if you are lokking from the inside out, or from the inside out. too many variables.

 

PS : for straight cuts like fitting louvre ventilators, I use the andle grinder fitted with a cutting disc. 9" or 4" depending on size of hole and accessibility. just make sure the sparks don't cause a fire or marks on the furniture

 

ive got a city and guilds for diggin holes

there's a lot of us on this forum who are good at digging holes for themselves. ................... I am not excluded.

[blueprince]

I have mulitple holes for sale, all sizes and makes, supply specifications and I will give you a quote.

 

for a guide, a five inch hole will cost you £15, with the cost rising at the cube of the diameter.

[Greybeard]

One to ponder on a sunny Sunday afternoon with beer in one hand and something cremated from the barby in 'tother..............is there any such thing as half a hole?

[tidal]

In addition to all the advice above also remember NOT to drill holes below the waterline whilst the boat is in the water

 

 

 

 

and yes, I HAVE seen that done

[BlueStringPudding]

ive got a city and guilds for diggin holes

 

I've got a city and guilds for talking through mine.

[Timleech]

In addition to all the advice above also remember NOT to drill holes below the waterline whilst the boat is in the water

 

 

 

 

and yes, I HAVE seen that done

 

When a group of us got together in 1965 to buy a boat, we bought a wooden L&L Short Boat which had been demotorised and no longer had a cooling water inlet (seacock).

The guy at the local boatyard (Bev Portman in Timperley) described to us how to drill the holes and fit the valve whilst in the water. As it happens we didn't need to do it but it seemed a fairly daunting prospect for us young innocents.

I'd have no qualms about doing it now, though, if the need arose.

Thorough preparation and confidence are both needed.

 

Tim

[tidal]

Yeah

I KNOW it CAN be done

 

But the last time I saw it done accidentally was in a marina in 6m of harbour water......

and no preparation

It was funny later