Base plate...sacrificial edge

[Bobbybass]

I have been blacking my boat today...all alone in a huge dry dock in Worsley.

All alone...that is..apart from a strange guy in a green boiler suit...who turns up smoking...and nobody else seems to see him...?

Is this going back to the ' do you belive in ghosts thread' ?

 

I wondered why..the base plate projects..sticks out.. about 1.5 inches all around the boat...and looked it up on the net.

One site said it was a 'sacrifial anode'. ?

That being the case.....should it be blacked ?

 

bob

Edited September 6, 2011 by Bobbybass

[RLWP]

It is sacrificial, but it isn't an anode. It is there to wear away against the sides of locks, against sloping canal bottoms, rocks and stuff. It protects the 'corner' of the hull (chine) from getting worn off

 

Black it

 

Richard

[Smelly]

I have been blacking my boat today...all alone in a huge dry dock in Worsley.

All alone...that is..apart from a strange guy in a green boiler suit...who turns up smoking...and nobody else seems to see him...?

Is this going back to the ' do you belive in ghosts thread' ?

 

I wondered why..the base plate projects..sticks out.. about 1.5 inches all around the boat...and looked it up on the net.

One site said it was a 'sacrifial anode'. ?

That being the case.....should it be blacked ?

 

bob

 

It's not the anode ut it is sacrificial; it stops you wearing the welded corners away...

 

Black it. Don't black the grey its welded on with "wings" they're the anodes!

[blackrose]

It's not a sacrificial anode, it's a physically sacrificial. Imagine if it wasn't there... it might not take long to wear through the corner if you scraped it a lot.

 

Since I wasn't blacking the baseplate I just blacked mine up to the edge.

[Timleech]

1.5" is an awful lot.

Depending on the shape of your hull, there could be a risk of it jamming in masonry on locksides.

Not that I want to get you worried or anything like that

0.5" to 0.75" would be much more usual.

 

Tim

[Ally]

it shouldn't be 1 1/2" wide though!!! I think the maximum is 12mm otherwise it becomes a hazard. I'll check the official maximum.

[Bobbybass]

It is sacrificial, but it isn't an anode. It is there to wear away against the sides of locks, against sloping canal bottoms, rocks and stuff. It protects the 'corner' of the hull (chine) from getting worn off

 

Black it

 

Richard

 

Aha..understood...a different kind of sacrifice..

[Timleech]

it shouldn't be 1 1/2" wide though!!! I think the maximum is 12mm otherwise it becomes a hazard. I'll check the official maximum.

 

Whose?

Never heard of such a thing, but I agree 1.5" would be too much for many hulls.

 

Tim

[Bobbybass]

1.5" is an awful lot.

Depending on the shape of your hull, there could be a risk of it jamming in masonry on locksides.

Not that I want to get you worried or anything like that

0.5" to 0.75" would be much more usual.

 

Tim

 

Its definatley 1.5 inches...and is a Reeves hull.

Its 1997 and has done 7300 hours... I haven't pranged it yet..but thanks for your concern.

 

bob

[Ally]

Whose?

Never heard of such a thing, but I agree 1.5" would be too much for many hulls.

 

Tim

As a boat builders standard for safety.....There was a recentish case of a boat getting trapped on the side of a lock because of too deep an underhang, and a recommendation was brought in following the safety investigation. Not quite sure what the measurement was but will find it tomorrow.

[RLWP]

Its definatley 1.5 inches...and is a Reeves hull.

Its 1997 and has done 7300 hours... I haven't pranged it yet..but thanks for your concern.

 

bob

 

Photo please

 

Richard

[alan_fincher]

Its definatley 1.5 inches...and is a Reeves hull.

Its 1997 and has done 7300 hours... I haven't pranged it yet..but thanks for your concern.

 

bob

 

I agree with those who say a 1.5" overlap each side is scarily large.

 

We ended up in a very nasty incident with a lot less overhang than that.

 

Of course it depends to no small extent how much your hull tapers towards the base plate - if it were built "Birmingham Square" then you could well have issues, as the baseplate might well prove to be the widest part.

 

Have you measured total width across the baseplate, to include these edges ? It certainly needs to measure less across the baseplate than the overall width of the hull over guards at the widest point higher up.

[nb Innisfree]

We have about 1"-1.5" overhang, doesn't make the boat any wider as the baseplate is a standard width anyway, it just means the hull side has been set in a bit more than usual, gives slightly less width inside.

 

One advantage is having room to weld a couple of extra anodes without increasing boat width.

[alan_fincher]

We have about 1"-1.5" overhang, doesn't make the boat any wider as the baseplate is a standard width anyway, it just means the hull side has been set in a bit more than usual, gives slightly less width inside.

 

One advantage is having room to weld a couple of extra anodes without increasing boat width.

Generally I agree, but I don't think there is one "standard" width for base-plates, although probably one is more common than the others.

 

The Inland Boat Owners Book reports most are 6'6" or 2 metres, but that those built "Birmingham Square" can have a baseplate of a full 6' 10".

 

Equally it explains that some fold the sides near the bottom, so only have an actual baseplate of 6'.

[nb Innisfree]

Generally I agree, but I don't think there is one "standard" width for base-plates, although probably one is more common than the others.

 

The Inland Boat Owners Book reports most are 6'6" or 2 metres, but that those built "Birmingham Square" can have a baseplate of a full 6' 10".

 

Equally it explains that some fold the sides near the bottom, so only have an actual baseplate of 6'.

 

Yes I think most baseplates are based(?!) on a standard 2m wide steel plate.

 

Was Birmingham Square perhaps based on old steel width of 6'10"? I am just guessing here.

Edited September 6, 2011 by nb Innisfree

[Mac of Cygnet]

I have a projection of the baseplate just like this, (Mick Sievewright 'Owl Class' boat, 1985) and was advised by the surveyor when I bought the boat to have this removed. I saw no reason to do this, and in fact it provides me with some peace of mind when lying in bed listening to it grinding against sloping moorings. I have been hung up on lock projections by the (rounded, so soon came off) edge of the gunwale, but never by the baseplate. As has been said, the angle of the side below thw waterline is the decider.

[Timleech]

As a boat builders standard for safety.....There was a recentish case of a boat getting trapped on the side of a lock because of too deep an underhang, and a recommendation was brought in following the safety investigation. Not quite sure what the measurement was but will find it tomorrow.

 

I'm still mystified by this 'recommendation brought in' business. Recommendation by whom to whom?

I'm not aware that there is a body which has any sort of control over such things, though I entirely agree that too much projecting bottom edge can be A Bad Thing.

 

Tim

[nb Innisfree]

I am assuming that the risk of a deep overhang getting caught up is down to the idea that the baseplate is wider than normal, is that what we are talking about. If so then a standard width base plate with the sides set in further is not a risk?

[David Schweizer]

As no one else seems to have mentioned it, the official name for the projection you are describing is "Sacraficial Chine" those on our boat are more like 1" wide except on the edge of the swims, where they are a bit wider. But we do have about a 1" tumblehome on the hull so coupled with at least 0.5" rubbing strakes, the chines are still within the overall profile of the hull.

[Timleech]

I am assuming that the risk of a deep overhang getting caught up is down to the idea that the baseplate is wider than normal, is that what we are talking about. If so then a standard width base plate with the sides set in further is not a risk?

 

Depends on the manner of the setting in. The risk of something causing an unexpected list has to be allowed for, it has been known to cause problems.

 

Tim

[billS]

Last week in Cobblers lock - I noticed an orange plastic bag tied to the lock ladder - strange I thought - how did that get there?

 

As the lock started to fill, the boat started to heel. We dropped the paddles sharpish and emptied the lock.

 

The ladder had come loose and our sacrificial chine had stuck underneath it. Obviously the orange bag was meant as a warning!

 

when we came back through the lock a few days later, the ladder had been cut away

[nb Innisfree]

Last week in Cobblers lock - I noticed an orange plastic bag tied to the lock ladder - strange I thought - how did that get there?

 

As the lock started to fill, the boat started to heel. We dropped the paddles sharpish and emptied the lock.

 

The ladder had come loose and our sacrificial chine had stuck underneath it. Obviously the orange bag was meant as a warning!

 

when we came back through the lock a few days later, the ladder had been cut away

 

Of course, I was thinking of getting caught when going down which a deep sacrificial chine wouldn't play a part in, but going up is a different story.

[RLWP]

Of course, I was thinking of getting caught when going down which a deep sacrificial chine wouldn't play a part in, but going up is a different story.

 

It does though. There have been narrowboats left hanging when the chine catches up on projecting brickwork

 

Richard

[nb Innisfree]

It does though. There have been narrowboats left hanging when the chine catches up on projecting brickwork

 

Richard

 

Yes I can see that a chine could do that but I was considering a wide chine versus a narrow one which I would have thought wouldn't make much difference, whereas a boat without a chine would be safer.

[RLWP]

Yes I can see that a chine could do that but I was considering a wide chine versus a narrow one which I would have thought wouldn't make much difference, whereas a boat without a chine would be safer.

 

Strictly speaking, you can't have a boat without a chine. It could be a very rounded chine of course

 

Richard