Broom Hire Fleet Wash

[Wildfuzz]

Dead giveaway to the rangers when I cross Hickling............... However very little wash!!!!!

[Jbx5]

Hi Mark the first new Broom 35s for the hire fleet that we're built 3 or 4 years ago (may be the same now?) had fitted 200hp engines with a view to sell off private after a few years 

We have the same hull on our Westwood (if fact went  past you at the weekend on Endeavour did sound the horn as you were strategically fitting a new flag off the side deck)!  This has a 150hp engine which once you push it a bit will create a large wash,  they are semi- displacement hulls.

As stated at normal cruising speeds they don't seem to create any more wash than our last boats though.

Regards John

 

 

[ExSurveyor]

Just now, Jbx5 said:

Hi Mark the first new Broom 35s for the hire fleet that we're built 3 or 4 years ago (may be the same now?) had fitted 200hp engines with a view to sell off private after a few years 

We have the same hull on our Westwood (if fact went  past you at the weekend on Endeavour did sound the horn as you were strategically fitting a new flag off the side deck)!  This has a 150hp engine which once you push it a bit will create a large wash,  they are semi- displacement hulls.

As stated at normal cruising speeds they don't seem to create any more wash than our last boats though.

Regards John

 

 

Was that the large pink  flag.  

I did hear a horn,  sorry I didn't wave. 

[JennyMorgan]

Hardly the perfect hire or Broads boat by the sound of it, looks good though.

[Vaughan]

To make a plug and a mould tool for a GRP hull is very expensive and so you need to sell a lot of them. Broom boats have tended to be semi-displacement so that they can be sold as river boats (private and hire) as well as offshore performance boats. To make a pure river boat hull nowadays would be difficult to make a profit, which is why so many new designs are still done on older moulds, with a new superstructure.

Wash has to do with two main things.

A displacement hull is low wash, but it has a hull speed, beyond which it will not go. A semi-displacement will lift out of the water and almost plane, but they are difficult to steer slowly in shallow water and make a lot of wash.

The other thing is water-line length or "wetted surface" which is related to speed. So a lovely old displacement river boat such as a Herbert Woods Queen of Light will glide past at 7MPH without disturbing the water whereas a day launch at 5MPH will plough along with its bow in the air making an enormous amount of wash.

Another question of "horses for courses".

It can also have a lot to do with "squat effect". I know JM always likes me to mention that!

[MauriceMynah]

Yes indeed Vaughan, JM likes few things more than a good Squat.!

[ExSurveyor]

23 minutes ago, Vaughan said:

To make a plug and a mould tool for a GRP hull is very expensive and so you need to sell a lot of them. Broom boats have tended to be semi-displacement so that they can be sold as river boats (private and hire) as well as offshore performance boats. To make a pure river boat hull nowadays would be difficult to make a profit, which is why so many new designs are still done on older moulds, with a new superstructure.

Wash has to do with two main things.

A displacement hull is low wash, but it has a hull speed, beyond which it will not go. A semi-displacement will lift out of the water and almost plane, but they are difficult to steer slowly in shallow water and make a lot of wash.

The other thing is water-line length or "wetted surface" which is related to speed. So a lovely old displacement river boat such as a Herbert Woods Queen of Light will glide past at 7MPH without disturbing the water whereas a day launch at 5MPH will plough along with its bow in the air making an enormous amount of wash.

Another question of "horses for courses".

It can also have a lot to do with "squat effect". I know JM always likes me to mention that!

I knew a technical bod would know the answer. Thanks Vaughan

[Vaughan]

Another factor for a river boat (a displacement hull) is the shape of the bottom at the stern. "normal" Broads designs can be seen to make a lot more wash from the stern than they do from the bow, especially if they have a hard chine, which tends to "knock down" the bow-wave.

Herbert Woods - and some others - had the trick of bending the bottom up towards the stern, so that the boat only draws about 2 inches across the transom. The water then flows cleanly off the bottom without pulling up a stern wave.

Have a look at photos of Water Rail and you will see what I mean.

This is more difficult to build in a wooden boat as the planks have to steamed to shape but, coupled with a balanced yacht type rudder, the result is well worth it.

[LondonRascal]

Different boats do create different wash patterns - this is all based on the hull design and can be rather noticeable. Of course the more speed the greater wash, but once wash is being thrown up this is where it shows.

Some boat builders have tried different approaches to 'low wash' hull designs and you see how their bows have various shapes to them. However, it not all about the bow it is the underwater profile and transom too. 

On Broad Ambition her underwater profile as one goes towards the stern rises up and also narrows and curves thus reducing drag compared to a stern that does not and has a 'guillotined' transom.  The effect of this drag and 'stern wave' is very noticeable when compared to the Jewel of Light boats that accompany us on our annual 'Lads Week' and at the same speed will create more wash than Broad Ambition. 

I think more emphasis generally should be placed on wash - it seems that we hear a lot about speed and providing Rangers with Radar Guns and working around the rivers with speed traps to try and enforce the speed limits which seems rather a lot of things to and spend out on to reduce wash through reduced speed which could be done through more information/education on what wash can cause, but that is just my personal opinion.

I was always taught if you are making a breaking wash, then slow down and regardless always slow for moored boats and where possible give Anglers a wider berth and slow too. I do that to this day and this came from the old guides that would accompany your booking confirmation back in the day.

*As ever Vaughan beat me to it and explained it far better

[ranworthbreeze]

3 hours ago, Gracie said:

I do apologise Mark, you started this topic about boat design and because of me it seems to have wondered onto speeding boats, I don't know what came over me, I never usually go off topic

Grace

Grace off topic, that's a new one not!

Regards

Alan

[ScrumpyCheddar]

8 hours ago, Gracie said:

"Lucky Gem"......I know most of the Ricko's fleet inside out and never heard of that one, perhaps she should be renamed Lucky in that Scrumpy didn't catch up with them  

Speed does seem to be more of a problem on the South, whether it be hire, private or whatever boat design, ignorance comes in all walks of life, to not slow down passing moored boats can be dangerous with little ones or less able bodied people on board especially. Many years ago we were moored at Brammerton, my Nan nearly went overboard because of someone speeding and too close, it's not just the wildlife and the bank erosion that's in danger when boaters ignore the speed limits

Grace

Gracie the wife has informed me it was Amber Gem 2.... and it had a chap on the back playing his guitar.... as it went flying by lol...

[JawsOrca]

Back on this one for me .. Orca is a deep vee semi displacement hull and I think everyone knows how much trouble she is to handle now, she needs to be moving to stay between the banks.. I'm well aware of how much wash she can make although I think shes pretty good if we stick below the limits.. in fact she produces a lot less wash.. The same for the other one, at senisble speeds it's really good and on tick over it produces nothing.. so sorry to say but I think it's a speed thing.. if your boat is producing too much wash then your are going too fast no matter what GPS's, rev measurements etc... 

[ExSurveyor]

My little Broom produces a lot of wash due to the hull design,  because of this I slow down when passing moored boats,  I judge it by the wake not the speed. 

I guess I have answered my own question 

 

[Hockham Admiral]

22 hours ago, Vaughan said:

Another factor for a river boat (a displacement hull) is the shape of the bottom at the stern. "normal" Broads designs can be seen to make a lot more wash from the stern than they do from the bow, especially if they have a hard chine, which tends to "knock down" the bow-wave.

Herbert Woods - and some others - had the trick of bending the bottom up towards the stern, so that the boat only draws about 2 inches across the transom. The water then flows cleanly off the bottom without pulling up a stern wave.

Have a look at photos of Water Rail and you will see what I mean.

This is more difficult to build in a wooden boat as the planks have to steamed to shape but, coupled with a balanced yacht type rudder, the result is well worth it.

Our Freeward 30 was a "double-ender" as the Americans say, or a "canoe-stern" as others might. At 5 kts (below) her stern wake was negligible.

[JennyMorgan]

John, a very tasteful boat is that, ideal for both the Broads and a spot of coastal cruising.

Wash wise, take a peep at Martham's boats as they go by, their builders/designers sorted the wash problem out years ago. It can be done, they handle well at slow speeds too!

[Hockham Admiral]

1 hour ago, JennyMorgan said:

John, a very tasteful boat is that, ideal for both the Broads and a spot of coastal cruising.

Wash wise, take a peep at Martham's boats as they go by, their builders/designers sorted the wash problem out years ago. It can be done, they handle well at slow speeds too!

Coastal Cruising!

Brundall to the Channel Isles and return, down to Cornwall and Northern France. Then across to Belgium, Holland, Denmark and Germany. All on separate voyages!

Caught out in a genuine F9 by mistake in the middle of the North Sea when a passing Ferry came up on Ch 16 and asked if we were in "difficulties". "No" I replied "but the ruddy G&T's spilt over!"

Halcyon days!