Jump to content

Tipping slighly to Port!!


Nb Smudger
 Share

Featured Posts

Hi All,

Hope you are all enjoying the Summer despite the mixed weather. Not getting far North on the Lancaster Canal at the moment, based at Garstang and can't get far past Lancaster due to the leak near the Lune Aqueduct. Anyway, a bit of advice please. I have a 40 foot JD hull self build completed in Jun 09. Since buying the boat in Aug 13 on a few occasions when passing other boats going in the opposite direction, I get this slight tipping to port. It's worse when I'm on a narrow stretch and I tend to slow down to tick over to assist. Of course not everyone coming the other way does. It's worse when you meet a large widebeam!! (there's a few trip boats on the Lancaster,) tipped about 30 degrees to port on one occasion! Again if they slow considerably, tipping is only slight.

 

I try to keep the water tank (bow) between half & full (150 gall when full), so a bit more weight there, not sure if that helps? Fuel tank (40 gall - stern) is full most of the time. Could that be the problem, too much weight at the stern? All the correct Certificates of Conformity etc etc were issued at time of build.

 

Chatting with other local users they reckon that other boats are "stealing" the water, especially when there isn't a lot of depth and worse still if it's a widebeam. Guess it's a case of slowing down even more!!

 

Any ideas / comments would be greatly appreciated.

 

Cheers.

Nb Smudger.

Link to comment
Share on other sites

I really would doubt it was as much as 30 degrees.

 

The issue is indeed the hydrodynamic effects as the boats pass each other, and will be affected by the shape of the canal bottom and how much of the cross section the two boats occupy. I'd be surprised if fiddling around with tanks etc would make much difference. Have you tried steering closer to the boat coming the other way - that may also encourage them to slow down a bit...

Link to comment
Share on other sites

I really would doubt it was as much as 30 degrees.

 

The issue is indeed the hydrodynamic effects as the boats pass each other, and will be affected by the shape of the canal bottom and how much of the cross section the two boats occupy. I'd be surprised if fiddling around with tanks etc would make much difference. Have you tried steering closer to the boat coming the other way - that may also encourage them to slow down a bit...

 

Hydrodynamic effects aside, the result I regularly find with my 33" draught boat is simply the hull temporarily sitting on the sloping bottom of the canal. Since most pass port to port this often induces a tilt to port due to canal profile, when the passing boats excess speed pushes away the water I was previously floating in.

 

A secondary effect is the bow being pulled into the water immediately behind the passing boat, often requiring a lot of helm to correct. Sadly sometimes their wash is enough to push me over and leave me aground though.

Edited by by'eck
Link to comment
Share on other sites

Yes it's due to the fact that boat's propulsion lowers the local water level by pushing water back behind the boat - that water has to come from somewhere and on shallow canals due to limited space between hull and canal bed the pushed-back water can't be replaced quickly enough, hence the local lowering of water level.

 

As your boat encounters the level reduced by both boats it may go aground on the offside, causing the tilt.

 

The effect depends on how much power each boat is applying so it will be helped if you reduce power, but it may still happen if the other boat has a lot of power on and/or you are too close to the side.

Link to comment
Share on other sites

Hi, thanks everyone. That's really helpful. Good idea Scholar Gypsy about steering closer to the oncoming boat!! Thanks for that, & thanks Frangar - I'd forgotten about the Saucer Shape bit! Think that was in WW a few years ago.

Thanks again everyone, probably be back on here again soon - planning a big trip to the Thames for next year (should be deeper water there!!), so might need a few good tips on routes etc. And then there's the Ribble Link!! OMG. Nb Smudger.

Link to comment
Share on other sites

Our boat leans to port after SWMBO has been to tesco. I call it a shopping list.

A boat behaving in the way described is almost certainly touching the canal bed. Happened to us twice today.

Link to comment
Share on other sites

Hi Mango, thanks for the comment. No, the engine is a Beta 28 with 750 hours. Seems to push the boat along ok. Hoping to travel down the Ribble Link next year & I understand you have to maintain a steady 2200 revs whilst on the Ribble? So I'll be doing a few tests for that beforehand!! But yes, the power seems ok. Cheers. Nb Smudger.

Link to comment
Share on other sites

I really would doubt it was as much as 30 degrees.

 

The issue is indeed the hydrodynamic effects as the boats pass each other, and will be affected by the shape of the canal bottom and how much of the cross section the two boats occupy. I'd be surprised if fiddling around with tanks etc would make much difference. Have you tried steering closer to the boat coming the other way - that may also encourage them to slow down a bit...

 

Now THERE I really do agree with you old boy.

I'm also thinking that passing closer together might cause them to try and stick together! Then, no-one's steering anywhere until they finally 'un-granch' each other and float on.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.