Weed-hatch freeboard

[turnbuttonboy]

I have been hunting around trying to find out the minimum freeboard required for a weed-hatch but have not managed to find anything definite. With our counter just submerged ours is only 75mm and, when underway hard, water drives in despite the extra addition of four G clamps! Clearly I am going to have to extend it but by how much in order to meet the relevant regs?

 

Many thanks Giles.

[blackrose]

I have been hunting around trying to find out the minimum freeboard required for a weed-hatch but have not managed to find anything definite. With our counter just submerged ours is only 75mm and, when underway hard, water drives in despite the extra addition of four G clamps! Clearly I am going to have to extend it but by how much in order to meet the relevant regs?

 

Many thanks Giles.

 

You mean the distance from the waterline to the top of the weedhatch? I think mine is about 8". I can't see any advantage of having less freeboard. Do you have neoprene or rubber seals between the top of the hatch and the lid?

Edited August 9, 2008 by blackrose

[alan_fincher]

I can't see any advantage of having less freeboard.

 

It depends on the type!

 

If like us you are unfortunate enough to have an "under counter" type, where there is no lift up plate in the rear deck, then the more "tunnel" above the water, the less space between the top of the hatch, and the bottom of the counter, and the further down you have to reach to get to the prop and shaft. Ours is definitely only usable by contortionists.

 

My son and I having only a couple of hours ago tried to wrestle a full set of jogging bottoms from blades and shaft, can definitely confirm that less "freeboard" would be an advantage on ours.

 

Mind you 3" doesn't sound a lot of margin. But if it has proper seals, it simply should not leak (at all) with the cover on, even with the measurements you have.

 

Alan

 

(Currently navigating in heavy rain, and battling with detritus n the canal near Leicester).

[John Orentas]

I have been hunting around trying to find out the minimum freeboard required for a weed-hatch but have not managed to find anything definite. With our counter just submerged ours is only 75mm and, when underway hard, water drives in despite the extra addition of four G clamps! Clearly I am going to have to extend it but by how much in order to meet the relevant regs?

 

Many thanks Giles.

 

 

Hi Giles.

 

75mm isn't too bad unless it is a very small boat, your problem is the sealing of the hatch, many builders use gasket material which is far too thin, ideally you need a 12mm thickness of neoprene, butyl or similar.. Take a look at the clamping mechanism which should have plenty of power, a robust design yet still be 'quick release'.. Try also to cut the gasket from a single sheet rather than strip and as a full rectangle with no joints, a coat of bitumen below it will retain it in position.

 

Even boats with 200mm free-board as Blackie mentions will still be prone to 'swamping' if the hatch seal is not good.

 

There are few 'standards' in boatbuilding, individual builders design what they think is the best system.

Edited August 9, 2008 by John Orentas

[blackrose]

It depends on the type!

 

If like us you are unfortunate enough to have an "under counter" type, where there is no lift up plate in the rear deck, then the more "tunnel" above the water, the less space between the top of the hatch, and the bottom of the counter, and the further down you have to reach to get to the prop and shaft. Ours is definitely only usable by contortionists.

 

I don't think I've ever seen the 'under counter' type. I can't quite picture it - does anyone have any pictures? Is there any reason for what sounds like this awkward design?

Edited August 9, 2008 by blackrose

[MikeV]

I'm not on the boat at the moment, but I'm sure our weedhatch freeboard is not more than about 4". As others suggest, I would look to the sealing material.

 

Ours is about an inch wide but only 2-3mm thick and made of some kind of closed cell foam plastic. It's very soft and deforms easily to accommodate the undulations in the weedhatch cover plate. I always check the weedhatch clamp at the same time as I turn the stern greaser to make sure it hasn't loosened during the day. There's sometimes a few drips, but nothing to worry about.

 

I assume your baffle plate is a reasonably tight fit and flush with the bottom of the counter? This should take most of the turbulence from the prop so it is only residual pressure that the top plate has deal with as the stern digs in at higher revs. //Mike

[John Orentas]

I don't think I've ever seen the 'under counter' type. I can't quite picture it - does anyone have any pictures? Is there any reason for what sounds like this awkward design?

 

 

My boat was like that, the builders 'standard' had and additional hatch on the deck, I considered it to be a rust trap and also it is a very long way down from deck to prop. (unless you are an Orangutan). In practise it is not too bad, the technique is to slide along the counter until you are above the hatch.. A good incentive not to store junk on the counter.

[tosher]

Ours is about an inch wide but only 2-3mm thick and made of some kind of closed cell foam plastic. It's very soft and deforms easily to accommodate the undulations in the weedhatch cover plate. I always check the weedhatch clamp at the same time as I turn the stern greaser to make sure it hasn't loosened during the day. There's sometimes a few drips, but nothing to worry about.

 

Sounds about like mine, I also smear the joint with a thin film of grease when replacing it and it has never leaked a drop. Strange though that on the occasions I have removed the hatch cover I have had a bit of a struggle to break the seal, neading a couple of screw driver blades to lever it open? tosher

[turnbuttonboy]

Thanks for the above replies - our problem is that we pull the stern down by more than three inches when hard underway. The idea of having the top of our weed hatch below the water line gives me the heebie jeebies, hence the reason that I asked if there was an industry standard. It would seem by the replies so far that there isn't one so I will just extend it by 100 mm. We do have a baffle plate and the neoprene seals are in good condition having been replaced a few weeks ago but there is little pleasure in cruising when concerned about the possibility of calamity!

 

Many thanks Giles.

[smileypete]

Thanks for the above replies - our problem is that we pull the stern down by more than three inches when hard underway. The idea of having the top of our weed hatch below the water line gives me the heebie jeebies, hence the reason that I asked if there was an industry standard. It would seem by the replies so far that there isn't one so I will just extend it by 100 mm. We do have a baffle plate and the neoprene seals are in good condition having been replaced a few weeks ago but there is little pleasure in cruising when concerned about the possibility of calamity!

 

How are you going to extend it?

 

cheers,

Pete.

[tugstyle]

I have been hunting around trying to find out the minimum freeboard required for a weed-hatch but have not managed to find anything definite. With our counter just submerged ours is only 75mm and, when underway hard, water drives in despite the extra addition of four G clamps! Clearly I am going to have to extend it but by how much in order to meet the relevant regs?

 

Many thanks Giles.

 

 

I think ours is also 'under the counter':

 

 

Our survey report describes the upper lip as being a 'satisfactory height above normal waterline'

 

Also no 'cover plate' just a 'lower splash plate' which is sealed with a gasket:

 

 

 

And from the outside:

 

 

I have not yet had the pleasure of using it but it looks really awkward!

 

Thanks

 

tugstyle

[Dorlan]

From the BSS web site...

A weed hatch, if not properly secured, can allow water into the bilges of a boat,

which could ultimately cause it to sink. It's advisable for privately owned boats

to have a secure and watertight weed hatch which reaches to at least 150mm

(6ins) above the waterline, when the boat is loaded up as normal.

[ChrisPy]

you won't like the answer, but according to ISO-12217 the minimum height of a downflooding opening above the waterline is 40cm, unless the hatch is secured according to ISO-12216. In that case it may fall in Area 1 zone, and the distance may be reduced to 20cm. So yes, there is an industry standard, but you will have to research it a bit. Both these ISOs are relevant to RCD requirements.

[turnbuttonboy]

you won't like the answer, but according to ISO-12217 the minimum height of a downflooding opening above the waterline is 40cm, unless the hatch is secured according to ISO-12216. In that case it may fall in Area 1 zone, and the distance may be reduced to 20cm. So yes, there is an industry standard, but you will have to research it a bit. Both these ISOs are relevant to RCD requirements.

 

 

That looks like the kiddy - I have searched for these on the BSS website but either lack your finesse or determination Chris!

 

It should be fairly simple to extend by bolting and welding a simple extension of the same dimension to the top of the existing hatch. The new securing clamps will be welded through to the old hatch which should mean that the whole piece is in compression when locked down. According to the information forwarded by Chris, I will have to extend by at least 150mm to conform to the relevant ISO standard but this is no more work than extending by 100mm. The only drawback is that I will have to develop longer arms!

 

Many thanks for that Chris.

 

Giles.

[smileypete]

That looks like the kiddy - I have searched for these on the BSS website but either lack your finesse or determination Chris!

 

It should be fairly simple to extend by bolting and welding a simple extension of the same dimension to the top of the existing hatch. The new securing clamps will be welded through to the old hatch which should mean that the whole piece is in compression when locked down. According to the information forwarded by Chris, I will have to extend by at least 150mm to conform to the relevant ISO standard but this is no more work than extending by 100mm. The only drawback is that I will have to develop longer arms!

 

Many thanks for that Chris.

 

Hi,

 

I'd consider getting an extension piece made of 4" or 6" 'U' channel made up and bolt that on.

 

That way a short armed person won't be completely stuck if there is something tricky wound round the prop.

 

A lot of the RCD is directed toward offshore boats, so blindly applying it to narrowboats may well be a waste of time, effort and money.

 

cheers,

Pete.

Edited August 10, 2008 by smileypete

[ChrisPy]

A lot of the RCD is directed toward offshore boats, so blindly applying it to narrowboats may well be a waste of time, effort and money.

 

I am not quoting blindly from the ISOs that support the RCD, and if that was implied, then it was an ill-considered remark.

I am quoting from the specific requirements for Category D craft, which is what we are.

A fuller knowledge of the structure of the standards and the RCD itself would clearly demonstrate that all categories of craft are considered, with appropriate solutions for each.

 

............ but there will always be people who prefer to rubbish the industry standards that have been developed to try to make our boats safe to buy. Some (most?) of them have obviously never read them. They are the blind ones.

 

 

 

I have searched for these on the BSS website but either lack your finesse or determination Chris!

 

Many thanks for that Chris.

I suggest that the BSS should be considered a simplified and minimum requirement for inspecting existing boats. It is not the highest authority on the way new boats should be constructed. It does refer to many ISOs but not all.

 

I would go for 20cm freeboard with a secure fixing to the hatch, that should comply with both of the ISOs and with the RCD Category D.

[smileypete]

............ but there will always be people who prefer to rubbish the industry standards that have been developed to try to make our boats safe to buy. Some (most?) of them have obviously never read them. They are the blind ones.

C'mon Chris, the blind ones are boatbuilder and owners who can't or won't think for themselves, RCD or not.

 

 

The big getout is as you said yourself, these standards try to improve safety, rather than bring about a measurable improvement in safety.

 

Often the trying is done in an arbitrary and completely opaque way, with no reference to real life risk.

 

Even if they make no difference to safety or even make it worse, they will have achieved their aims of trying.

 

cheers,

Pete.

Edited August 10, 2008 by smileypete

[ChrisPy]

C'mon Chris, the blind ones are boatbuilder and owners who can't or won't think for themselves, RCD or not.

 

 

The big getout is as you said yourself, these standards try to improve safety, rather than bring about a measurable improvement in safety.

 

Often the trying is done in an arbitrary and completely opaque way, with no reference to real life risk.

 

Even if they make no difference to safety or even make it worse, they will have achieved their aims of trying.

 

cheers,

Pete.

my word, you are cynical about the industry ..........

 

Compliance with standards is not optional, so regardless of your kite flying, builders have to comply. This applies to all products sold in Europe, not just boats.

 

I would like to hear which of the RCD-related ISOs tries to ensure safe standards in an arbitrary and completely opaque way. The ones I applied to my build were very clear and seemed to me to be perfectly logical and straightforward. I had already followed the advice given in several noteworthy sources such as Graham Booth, Tony Brooks and Nigel Calder. When I had to do my RCD DoC, I checked the relevant ISOs and I found compliance was already assured. This confirmed my view that the ISOs are no less and no more than the standards that the industry has agreed are good practice.

 

Of course some parts of the industry claim compliance when they either have no idea whether or not they comply, or are fully aware that they don't but no-one will pick them up. That is a matter for Trading Standards.

Edited August 10, 2008 by chris polley

[turnbuttonboy]

'C'mon Chris, the blind ones are boatbuilder and owners who can't or won't think for themselves, RCD or not.'

I do not think that many boat owners have any idea what standards apply to their craft. They trust that their builder understands and applies the relevant details and only go searching for information once their trust has been destroyed.

 

'the big getout is as you said yourself, these standards try to improve safety, rather than bring about a measurable improvement in safety.'

Had our builder applied them then we would not be concerned about our safety. I will feel safe once I have applied them. I may have even got my barge to Ireland this year if he had applied the relevant ISO standards throughout the build.

 

I will have to employ a surveyor to confirm that the new set up meets the relevant standards or risk one hell of a bad time from my insurer should anything go wrong.

 

Interesting argument but I am firmly with Mr Polley on this one.

 

Giles

[Petethelegs]

I have been hunting around trying to find out the minimum freeboard required for a weed-hatch but have not managed to find anything definite. With our counter just submerged ours is only 75mm and, when underway hard, water drives in despite the extra addition of four G clamps! Clearly I am going to have to extend it but by how much in order to meet the relevant regs?

 

Many thanks Giles.

 

Hi,

 

ideally should be 250mm above water line.

[denboy]

I think ours is also 'under the counter':

 

 

Our survey report describes the upper lip as being a 'satisfactory height above normal waterline'

 

Also no 'cover plate' just a 'lower splash plate' which is sealed with a gasket:

 

 

 

And from the outside:

 

 

I have not yet had the pleasure of using it but it looks really awkward!

 

Thanks

 

tugstyle

yep same as mine one tip worth remembering when you crack it open push/tip it away from you as you end up with a face full of smelly stagnant water