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Baggywrinkle

Cause For Concern?

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Whilst tacking down the Thurne from West Somerton last week, I overheard part of a conversation between 2 people on the bank: “All the major boatyards have forbidden hirers to go to West Somerton because of the weed.”

Does anyone know if this is true and if so how long it will last and whether it is a regular occurrence? There was evidence of weed cutting and the weed cutter was moored at West Somerton.

If no one goes, the BA may think of withdrawing the free moorings.

Many thanks.

Bruce

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I'll go, take 'B.A' and churn things up a tad.  4 x Blade prop, 50hp - that'll do it.  Never had a blocked weed filter to date as we have two pick ups, (Scoop type both with grills).  All I need now is a suitable airdraft to get under 'That' bridge

Griff

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3 hours ago, BroadAmbition said:

I'll go, take 'B.A' and churn things up a tad.  4 x Blade prop, 50hp - that'll do it.  Never had a blocked weed filter to date as we have two pick ups, (Scoop type both with grills).  All I need now is a suitable airdraft to get under 'That' bridge

Griff

Do you find the 4 Blade Prop to be better than a 3?  Will it produce increased thrust at lower revs compared to a 3 Blade given the extra surface area of the prop? 

Its a upgrade I often consider making but I dont understand the technicalities to weigh up any benefits, we also have a 50hp on a 37ft hull, 

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The very point I made to BA re Waxham Cut. Boats can get up there, they can turn, you can walk to the beach from the mill, but because of a notice at the entrance boats don't enter, therefore the weeds grow and it becomes less accessible etc etc. of course there will never be lots of boats  but every one makes a difference.  Broad Ambition with his prop would be very welcome . We have visited west somerton a number of times this year with no problems. 

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Weed on the upper reaches of the Thurne this year has been a major problem.  The warm weather in the early part of the season has led to rapid growth, and it just keeps coming.  The BA weed harvester has made several cuts towards West Somerton, in Waxham Cut, Catfield Dyke and on Hickling Broad, but they're struggling to keep pace with the growth.  The harvester also has to cut up towards Coltishall, and Dilham, where there are similar problems.

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I did attempt a trip to Somerton about a month and a half ago, but was stumped crossing Martham broad due to weeds so turned back.

I'm planning to use the boat tomorrow, so may venture that way, to see the difference.

 

 

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Do you find the 4 Blade Prop to be better than a 3?  Will it produce increased thrust at lower revs compared to a 3 Blade given the extra surface area of the prop? 

Most definitely - much easier for berthing, kicking the stern end in/out, towing etc.  We moved to four blades when we upgraded the powerplant to 50hp form the original 34hp.  There wasn't the room underneath to increase diameter size, so 4 x blades was the way to go.  She is now ever so slightly over propped as she should be

Griff

 

BA NBN 127.jpg

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We had 'B.A' out of the crinkly stuff to cure a leak on where the transom joins the bottom planking.  Whilst we were at it we decided to get rid of the original cast iron rudder.  It was heavy and every two years had to be wire brushed then anti-fouled, a laborious time consuming job.   The rudder stops or shark fins were also suffering.  All three items really needed grit/sand blasting again, the last time we did that process was during the restoration so more than ten years ago.

Griff

 

 

BA NBN 332.JPG

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The replacement stainless steel unit we had made was 25mm longer on the trailing edge and from the pin was raked up to follow the angle of the hull.  This gave the rudder a larger surface area.  It's weight was much less compared to the original unit, and no strengthening ribs were required so smoother with less drag too.  The result on the helm was much less effort, more responsive and a tighter turning circle (She will never match Malanka for that though).  The biggest improvement as far as I was concerned that when we take 'B.A' out for her bi-annual slipping, it is now a simple matter of just applying a jet wash, no more wire brushing and applying anti-foul

Griff

 

 

BA NBN 333.JPG

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Thanks for the propellor info Griff. How would I know what pitch to go for?  We also have a 50hp unit, would the same pitch as yours suit our boat to? 

Our rudder will be getting some attention with a wire brush wheel on a grinder this winter!  I think it might end up needing replacement before much longer.  

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I noticed when you were working on BA in spring the void in the steel behind the flow to the prop. Would you get a better clean flow to the prop by putting a cap on this void.

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I noticed when you were working on BA in spring the void in the steel behind the flow to the prop. Would you get a better clean flow to the prop by putting a cap on this void.

Probably but then I would not be able to get into it for cleaning / anti-fouling. If we were a racing boat then something would have to be done with it but it seems to flow fairly well through it.  The stern end of it is open and raised up to direct water to the face of the blades

Thanks for the propeller info Griff. How would I know what pitch to go for?  We also have a 50hp unit, would the same pitch as yours suit our boat to? 

Correct propeller size / pitch is a black art, one I'm not qualified in.  Jason Hatch however is the man, you would need to consult someone of his ilk.  It needs consideration with hull length / shape etc, not just the hp and g/box ratio

Griff

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10 hours ago, BroadAmbition said:

Correct propeller size / pitch is a black art, one I'm not qualified in.  Jason Hatch however is the man, you would need to consult someone of his ilk.  It needs consideration with hull length / shape etc, not just the hp and g/box ratio

Or Paul at clemments engineering, he knows most things prop and does a lovely job on them.

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Yup. Complicated calculation involving displacement, hull profile, desired top speed, desired minimum speed, engine output, gear ratio et al. I could probably figure it out mathematically but go to a prop expert and they can figure it out in minutes. By the way, 4 blades much better than 3 for broads speeds. It's akin to having a low ratio box like on a 4 x 4. Great for control.

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On 12/08/2017 at 17:24, johnb said:

The very point I made to BA re Waxham Cut. Boats can get up there, they can turn, you can walk to the beach from the mill, but because of a notice at the entrance boats don't enter, therefore the weeds grow and it becomes less accessible etc etc. of course there will never be lots of boats  but every one makes a difference.  Broad Ambition with his prop would be very welcome . We have visited west somerton a number of times this year with no problems. 

All part of the master plan.... :default_norty:

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