Who's Idea For Low Wash Hull?

[Andrewcook]

Who's Idea was it to put Low Wash Hulls that suppose to work as not making to much of a wash going along the River that did not work very well  now reverting back to the Old Style Type of Hull like B A and a few others Boats on the River that does not make to much of a wash . I believe these people who designs theses Low Wash hull did not do their research  properly before Building these Boats. Will these Old Style Design Hulls be coming back to stop the Bank erosions ?

Yours

Andrew Cook    

[Hockham Admiral]

Andrew, Hi.

They are low wash if kept below their displacement speed and then it's not the designer's fault for anticipating that peeps might try to exceed this .

At legal speeds I have noted that they are indeed low wash.

[JennyMorgan]

Of all the low wash hulls on the Broads those of the Martham boats built in the 1950's still take some beating. Their boats can really glide along!

[High6]

Apparently  "Wash is the disturbed water caused by the propeller or jet drive.  Wake is the disturbed water caused by
the motion of the vessel's hull passing through the water". Is it possible to distinguish between them with regard to Broads craft?

[Guest ExMemberKingFisher]

Low wash hulls really do reduce wash when used at the correct speed, however there is a very bad side effect of low wash hulls that was probably never anticipated. Try stern on mooring somewhere open like outside the Wherry hotel Oulton Broad on a windy night and sleep in the front berth with the wavelets heading towards the bow and listen to the constant slap slap as the water gets trapped and funnelled into the low wash grooves. Low wash hulls seem to be a lot harder to sleep with than conventional designs on a rough night.

[Guest]

Regardless of what type of hull it is be it displacement , semi displacement or planing if its operated outside of its design speed you will get wash .

Couldn't agree more about low wash hulls and noise when moored in choppy conditions one kept me awake and I wasn't even on it I was moored behind goodness knows how anyone slept onboard that night 

[MauriceMynah]

I like that noise ... it sends me to sleep like rain on the roof.

[Andrewcook]

Hi this is very interesting subject as to the Two things on this thread. One with V Shape Hull yes the  Cruisers do glide a long with out making to much awash. Two other point is I  was not aware that with Low wash Hull when moored up Stern on such Ranworth or any where else Keeps people  awake as to Sleeping in the front with water Slapping against it as I'm totally Deaf and don't have that bother but the Vibration does bother me when Mooring side on and having a Dinghy attached to the Boat such as at Reedham when it is Windy and get's rough.

Andrew Cook

[Poppy]

1 hour ago, KingfishersTime said:

Low wash hulls really do reduce wash when used at the correct speed, however there is a very bad side effect of low wash hulls that was probably never anticipated. Try stern on mooring somewhere open like outside the Wherry hotel Oulton Broad on a windy night and sleep in the front berth with the wavelets heading towards the bow and listen to the constant slap slap as the water gets trapped and funnelled into the low wash grooves. Low wash hulls seem to be a lot harder to sleep with than conventional designs on a rough night.

Interesting. I don't find that with my Broads yacht - and they don't come much 'lower wash' than those !

[JennyMorgan]

3 hours ago, Poppy said:

Interesting. I don't find that with my Broads yacht - and they don't come much 'lower wash' than those !

As one who, when out taking close-up action photographs, was caught in the trough created by Madie as she went past on a broad reach in a fair old puff I can only add 'not all'. Even Mike, the owner, thought that he'd finally got me!

[marshman]

Maidie at full clap is a sight to behold - as is her following wake.

I think what Polly meant was at normal speeds - all displacement boats will create a wash above hull speed and that includes sailing boats and day boats - especially!

[TheQ]

There are two ways of making a low wash Hull;

One is like sailing boats to have a smooth hull and create as little resistance to the water as possible,

The other is to have ridges on the hull to "consume" the bow wave.

The ridged boats are likely to be more noisy  from wavelets when trying to sleep.

The maximum waves produced are likely to be just before getting on the plane, the hull at that point is moving the most amount of water out of the way. Once planning you are on the water not in it, this is why something like Maidie, Not designed to plane, would make a huge hole in the water at speed.

The Elysian I have is of course a planning Hull, there are versions with enough power to do so. This does mean that they are not as smooth through the water at displacement spends.

[Malanka]

Low wash hull , simples. Wood, wood or er wood. 

 

The Silver Jubilees and the rest of the Martham fleet all have the same thing that we do, a water line Chine which really reduces the disturbance of the displaced water. We have a roiling wash from the prop but it's flat not rooster tailed (raised) at all as all that takes place quite far under the boat and it comes out flat with very little noise too.

 

When crossing Breydon at 10 mph we certainly demonstrate a huge wash and massive disturbances in the force (ooops ) water we can...

 

The Martham designs are IMO the lowest wash boats on the system. Look good and sound great too.

 

M

[ChrisB]

The Cathedral hull is very low wash but awful to live with at anchor or weighted as the smallest wavelet "plips and plops" all night, it can be so bad if head to wind on a mooring it can annoy other boats.

In other countries multi hulls are often used where wash is a sensitive issue. Take the Motorcat that is Canadian but now built in Poland. It's beam is 9ft 5ins so not a problem in Broads marinas, draft 1ft 7ins twin 10hp engines would supply all the power needed and the ability to put one ahead and one astern for close work.

[MauriceMynah]

My boat's just been washed.

[Malanka]

OMG did you go have a lie down?

[ChrisB]

But at the end of the day, in displacement boats it really boils down to waterline length. A 40ft waterline at 6mph will be next to nothing, a 17ft day boat at the same speed will push a wall of water like it were a waterbourne bulldozer.

As said before Square root of waterline length x 1.34 = knots

[Viking23]

11 minutes ago, MauriceMynah said:

My boat's just been washed.

Were you a "wake" at the time lol  ...?

 

 

[Viking23]

8 minutes ago, ChrisB said:

But at the end of the day, in displacement boats it really boils down to waterline length. A 40ft waterline at 6mph will be next to nothing, a 17ft day boat at the same speed will push a wall of water like it were a waterbourne bulldozer.

As said before Square root of waterline length x 1.34 = knots

Hi Chris, I must write that down... but is length in feet?

 

Richard

[MauriceMynah]

Yes, in feet.

I've lent Nyx to a friend of mine. He decided to wash it.  ...   I think I'll lend it to him again next year, but earlier in the season. :)

[TheQ]

The problem with Multihulls is the centre of the floor is too high, maybe a minimum of 1ft for clearance above the water. So if you add human height plus a little for the cabin roof and you are looking at a minimum of 8ft airdraft, that would stop you at a lot of the bridges..

[ChrisB]

6 minutes ago, Viking23 said:

Hi Chris, I must write that down... but is length in feet?

 

Richard

Yes, imperial, waterline length in feet. Multiply your answer by 1.15 to get mph.

Regards Richard,

Chris

[ChrisB]

Just now, TheQ said:

The problem with Multihulls is the centre of the floor is too high, maybe a minimum of 1ft for clearance above the water. So if you add human height plus a little for the cabin roof and you are looking at a minimum of 8ft airdraft, that would stop you at a lot of the bridges..

Do you actually need full standing head room in the centre where you sit and sleep? You have it in the hulls for the galley, heads, and single berths.

[TheQ]

With my back getting forward in a 4ft high cabin to sit or otherwise manoeuver would be a major problem. It certainly would be a hard sell in the hire fleet not having standing head room everywhere.

[CambridgeCabby]

1 hour ago, MauriceMynah said:

My boat's just been washed.

Will you recognise her next time you're down though ?

i thought green was the new white