Blacking bottom plate----OR NOT

[Eliza Jane]

This is our second used boat, but the first we have kept long enough to have the hull blacked on.

There seems to be some debate about blacking the bottom plate on Narrowboats.

Some say, because it's always immersed it doesn't rust nearly as much as at the waterline on the sides and therefore doesn't require blacking.

Also that it's very easy to rub the plate along the bottom of most canals and the blacking would be scraped off anyway.

She is 17 years old now and been looked after quite well, prior to us, and I want to carry on with the good care.

I'll be doing the blacking myself and would appreciate any thoughts.

Cheers.

[bigste]

I'd not wastecthe brass for all the reasons you mention. The sides will be rotted well before the bare bottom.

Edited November 30, 2014 by bigste

[MtB]

Steel baseplates rust perfectly well. Ask any surveyor.

 

Given the impossibility of blacking the whole baseplate without endless time in the dock shuffling about the stocks so the whole baseplate gets three coats, the usual idea is to simply have a thicker baseplate that will take longer to rust through.

 

MtB

[magnetman]

The base plate is also usually considerably thicker than other parts so to me it is pretty irrelevant whether it is painted or not because other areas are going to fail well before so more attention should be paid to those bits. Also the baseplate is going to be the bit which rubs on the ground so a paint coating is very difficult to maintain if the boat every goes anywhere.

 

thats what I think anyway.

 

of coursef the boat is an old one with 6mm or 1/4 inch plating for base and sides then maybe there is an argument for protecting the base as well. The general aggrevation involved in doing this with a cabined boat which you can't turn upside down seems to make it not worthwhile really.

wow.

 

3 posts during the same minute

 

great minds like a think

[Guest]

This is our second used boat, but the first we have kept long enough to have the hull blacked on.

There seems to be some debate about blacking the bottom plate on Narrowboats.

Some say, because it's always immersed it doesn't rust nearly as much as at the waterline on the sides and therefore doesn't require blacking.

Also that it's very easy to rub the plate along the bottom of most canals and the blacking would be scraped off anyway.

She is 17 years old now and been looked after quite well, prior to us, and I want to carry on with the good care.

I'll be doing the blacking myself and would appreciate any thoughts.

Cheers.

Is the base plate in good nick after 17 years?

Was the base plate blacked before?

If it appears to have never been blacked and is in good nick after 17 years, I would think it will be in good nick after another 17.

The bottom plate on our boat is like new after almost 11 years and has never been protected with anything. If ever it starts to show deterioration, I will spend the money having it blasted and epoxied.

[boots]

Baseplate a do rust, but as others have said just not as fast as the sides.. Personally my thoughts wold be: what condition is it in now? And has it been painted before? - that might give you a feel for whether it 'needs' doing. Then it is a case of a) can you afford it? is it feasible to do it (e.g. Can you get adequately access)?

 

For the record, we have ours done and previously we walked away from a boat we were looking to buy after the surveyor advised of the level of pitting on the base plate (and advised the re/over plating would be required)

 

Thought I would caveat my comments with the fact that we are still on our first boat (and still consider ourselves beginners)

 

Martin

[Eliza Jane]

So much info in such a short time span, thanks to all for replying.
She's not out of the cut yet so I can't say for sure if the base has been painted before or not, nor can I report on the condition yet.
It was sold to us with a 10mm plate and it's a very good comment that the sides will fail first.
It'll be a suck-it-and-see operation at best, she has mag anodes etc so fingers crossed.

I don't intend to do it until spring, just before we go out for the season.
I'm also looking for a 15 x 9 prop if anybody knows of one. She has a 14 x 9 at present and feels very under-propped, even on the Thames.

Thanks again.

[ditchcrawler]

So much info in such a short time span, thanks to all for replying.

She's not out of the cut yet so I can't say for sure if the base has been painted before or not, nor can I report on the condition yet.

It was sold to us with a 10mm plate and it's a very good comment that the sides will fail first.

It'll be a suck-it-and-see operation at best, she has mag anodes etc so fingers crossed.

I don't intend to do it until spring, just before we go out for the season.

I'm also looking for a 15 x 9 prop if anybody knows of one. She has a 14 x 9 at present and feels very under-propped, even on the Thames.

Thanks again.

Best you get a lift out booked then, If you want to do the base you will need somewhere where they stand them higher from the ground.

[dave moore]

Hi

 

I write as someone involved in the boat painting business, long term boater too. If you are thinking of doing it yourself, please ask " how". Most docks have little clearance underneath to actually get under and do the job ( all right, I know that Debdale on the Leicester line have suitable facilities ) and I'm not sure that in most cramped environments you'd have half a chance of doing a good enough job to make the struggle worthwhile. None of the builders I work with black the baseplate, though 10mm or 12mm or sometimes more is the norm here.

 

If you go for it..good luck! Let us know how you get on.

 

Dave

[Tim Lewis]

This is our second used boat, but the first we have kept long enough to have the hull blacked on.

There seems to be some debate about blacking the bottom plate on Narrowboats.

Some say, because it's always immersed it doesn't rust nearly as much as at the waterline on the sides and therefore doesn't require blacking.

Also that it's very easy to rub the plate along the bottom of most canals and the blacking would be scraped off anyway.

She is 17 years old now and been looked after quite well, prior to us, and I want to carry on with the good care.

I'll be doing the blacking myself and would appreciate any thoughts.

Cheers.

We always black the bottom of Fulbourne as it's 77 years old now and the last two surveyors can't agree how thick it is!

 

We do have the advantage of being fairly mob handed when we dry dock the boat but it is still no fun working lying in a puddle in an eighteen inch gap. We are looking forward to our next blacking at the new Aylesbury Canal society covered slipway which contains jacks to lift the boat well off the ground

 

Tim

Edited November 30, 2014 by Tim Lewis

[Eliza Jane]

Thanks Tim.

Fulbourne is just a bit older than me! Only just!

I'm used to lying in puddles and working above me, I used to build rally cars and service on events for crews in all weathers, now where did I put those waterproofs?

Cheers.

Rob.

Hi

I write as someone involved in the boat painting business, long term boater too. If you are thinking of doing it yourself, please ask " how". Most docks have little clearance underneath to actually get under and do the job ( all right, I know that Debdale on the Leicester line have suitable facilities ) and I'm not sure that in most cramped environments you'd have half a chance of doing a good enough job to make the struggle worthwhile. None of the builders I work with black the baseplate, though 10mm or 12mm or sometimes more is the norm here.

If you go for it..good luck! Let us know how you get on.

Dave

 

Thanks Dave.
Much appreciated, I'll try to let you know, especially how much blacking I get up my sleeves!

Rob.

[ditchcrawler]

There are some dry docks where you just wont manage it.

[Bloomsberry]

So far all I have heard about the benefits and pitfalls about blacking the baseplate has been theoretical. Has anyone got any evidence of it being a success / failure ie. taking the boat out of the water 6-12 months after the blacking and seeing how much is still in place ?

With the weight of the boat pressing down on any underwater debris, I can imagine the abrasion is pretty substantial. This being repeated several times during the year I can imagine is going to wreck any protection the blacking would be providing.

I've had the floor up in a few areas in my narrowboat and the amount of rust I've scrapped off the top of the baseplate has been incredible. I know rust expands a lot but the sheer weight of the flakes that were removed were pretty heavy, and all this used to be part of the baseplate ! Let's face it , the surface of the baseplate is pretty damp with loads of oxygen available.

Maybe the protection of the top of the baseplate is more important than the bottom ?

[furnessvale]

This is our second used boat, but the first we have kept long enough to have the hull blacked on.

There seems to be some debate about blacking the bottom plate on Narrowboats.

Some say, because it's always immersed it doesn't rust nearly as much as at the waterline on the sides and therefore doesn't require blacking.

Also that it's very easy to rub the plate along the bottom of most canals and the blacking would be scraped off anyway.

She is 17 years old now and been looked after quite well, prior to us, and I want to carry on with the good care.

I'll be doing the blacking myself and would appreciate any thoughts.

Cheers.

This question often gets asked and the answer is always the same.

 

When on dock you check the bottom. If it is rusty, clean and black it.

 

If it is shiny through rubbing along the cut, don't bother because your new blacking will go the same way.

 

With the (ex)working boats I am used to, I normally black from the bow towards the stern. About two thirds the way down I stop as the bottom is now getting shiny.

 

George ex nb Alton retired

[ditchcrawler]

This question often gets asked and the answer is always the same.

 

When on dock you check the bottom. If it is rusty, clean and black it.

 

If it is shiny through rubbing along the cut, don't bother because your new blacking will go the same way.

 

With the (ex)working boats I am used to, I normally black from the bow towards the stern. About two thirds the way down I stop as the bottom is now getting shiny.

 

George ex nb Alton retired

I happened to be at Debdale and they had just lifted a boat for blacking, putting it on the hi trestles I turned up just as they hit it with the hi pressure wash. The under side was covered in mussels, nothing had rubbed the bottom of that boat since it was last blacked.

[furnessvale]

I happened to be at Debdale and they had just lifted a boat for blacking, putting it on the hi trestles I turned up just as they hit it with the hi pressure wash. The under side was covered in mussels, nothing had rubbed the bottom of that boat since it was last blacked.

Exactly, and that may well be the normal case with many modern shallower draughted boats.

 

The stern end of an empty ex working boat will draw down to 3ft or more so the back third or quarter will often be rubbed.

 

George ex nb Alton retired

[Eliza Jane]

So far all I have heard about the benefits and pitfalls about blacking the baseplate has been theoretical. Has anyone got any evidence of it being a success / failure ie. taking the boat out of the water 6-12 months after the blacking and seeing how much is still in place ?

 

With the weight of the boat pressing down on any underwater debris, I can imagine the abrasion is pretty substantial. This being repeated several times during the year I can imagine is going to wreck any protection the blacking would be providing.

 

I've had the floor up in a few areas in my narrowboat and the amount of rust I've scrapped off the top of the baseplate has been incredible. I know rust expands a lot but the sheer weight of the flakes that were removed were pretty heavy, and all this used to be part of the baseplate ! Let's face it , the surface of the baseplate is pretty damp with loads of oxygen available.

 

Maybe the protection of the top of the baseplate is more important than the bottom ?

You could be right Bloomsberry, although I try to get as much ventilation through the floor to avoid condensation build-up, if it's dry it won't rust?

Exactly, and that may well be the normal case with many modern shallower draughted boats.

 

The stern end of an empty ex working boat will draw down to 3ft or more so the back third or quarter will often be rubbed.

 

George ex nb Alton retired

Thanks George, your experienced view is much appreciated. With the state of the dredging, or not, all our boats should have shiny bottoms.

[davey b]

Interesting comment about the inside of the base plate, I've just lifted the floor in the bathroom (rear-most before the engine room) and apart from a small patch by the shower waste there was no rust at all; the primer used to paint the interior of the boat has held up well in 12 years. If the floor hadn't been painted I wonder if it would have faired as well.

 

When it was out for blacking we decided against due to access though it seemed clean enough. (I'd bought the paint as well...)

Edited December 1, 2014 by davey b

[Troyboy]

The following is a quote from the survey I had on my boat when it was 28 years old and required a survey for insurance purposes .

'Pitting was noticed on the bottom plate up to no more than 0.4 mm. The bottom had been painted at some time past and this lack of pitting is testament to the advisability of this practice . Only minor pitting up to 0.3 mm was noted on the sides ,bows and swims . The steelwork is generally in remarkably good condition for its age .'

I always paint the bottom plate and yes it is a lousy job but I think the survey of my 28 year old boat highlights it is worth doing .

[Neil2]

As no-one seems to have picked up the prop question ... 15 x 9 is a pretty standard size of prop - are you having difficulties sourcing one?

 

But, rather than starting experimenting with prop sizes why not go to Crowthers with your engine and boat details they will advise you what size you should be running with.

[Athy]

Baseplate a do rust.

Yeah man!

I hadn't realised that we had any Jamaican colleagues on CWF!

[serenility]

We recently had serenity's sides and bottom grit blasted, metal sprayed and epoxy'd at debdale. I could never see the point of having the bottom plate done,but was persuaded, despite it more than doubling the cost to have it done by this argument:

After 20 years in the water there will be pits. the deepest pit which eventually goes right through is the one that sinks the boat. Grit blasting cleans the rust out of all the pits and the metal spraying and epoxy gets right into the pits.

Yes, as soon as you run aground, then some of the coatings are worn off exposing the steel to rusting, but not from the old pits. You are therefore virtually starting again in the 'fastest pit to the finish race'

Discuss!

Edited December 1, 2014 by serenility

[dave moore]

I'm not aware of any boats that have sunk because of a corroded baseplate, I'm sure someone will be along to contradict me soon!

 

Dave

[Neil2]

We recently had serenity's sides and bottom grit blasted, metal sprayed and epoxy'd at debdale. I could never see the point of having the bottom plate done,but was persuaded, despite it more than doubling the cost to have it done by this argument:

After 20 years in the water there will be pits. the deepest pit which eventually goes right through is the one that sinks the boat. Grit blasting cleans the rust out of all the pits and the metal spraying and epoxy gets right into the pits.

Yes, as soon as you run aground, then some of the coatings are worn off exposing the steel to rusting, but not from the old pits. You are therefore virtually starting again in the 'fastest pit to the finish race'

Discuss!

I sort of subscribe to that first theory but the other reason for zinc spraying is the alleged "self healing" properties of the coating if and when the underlying steel is exposed. I have seen controlled experiments where a galvanised surface has "repaired" itself across a gap of 6mm. So the theory is that pitting should be a thing of the past, or at least for ten years minimum.

 

i don't think there's any doubt that this works in salt water where the zinc forms protective compounds readily, what I'm not sure about is how well it works in fresh water. I'm guessing there's only a few dozen narrowboats on the system that have been hot sprayed, though there's possibly more than have been done with Zinga or similar. So I suspect the jury is out on this just now.

 

I'm still having it done though.

[ditchcrawler]

I'm not aware of any boats that have sunk because of a corroded baseplate, I'm sure someone will be along to contradict me soon!

 

Dave

We had one at Napton