Why do canoe's cause so much boat movement?

[Bettie Boo]

As per the title.

 

 

Can anyone explain to me why? I don't get it.

 

 

*** It's not a complaint, it's an observation that I don't understand why it happens.

 

Currently moored on the Tring summit, (no where near a lock) and have had numerous NB's pass at a variety of speeds and we have not moved. 4 canoes raced past and we were bopping all over the place.

 

This happens where ever we moor and are passed by multiple canoes/row boats

[magnetman]

As per the title.

 

 

Can anyone explain to me why? I don't get it.

 

 

*** It's not a complaint, it's an observation that I don't understand why it happens.

 

Currently moored on the Tring summit, (no where near a lock) and have had numerous NB's pass at a variety of speeds and we have not moved. 4 canoes raced past and we were bopping all over the place.

 

This happens where ever we moor and are passed by multiple canoes/row boats

It is quite impressive. I think its to do with the canoes (you probably mean kayaks) traveling at fairly high speed thereby causing significant displacement of water.

 

Because they are small looking one assumes they don't do a lot but if you look they are moving fast and they are not planing so they are displacing all the water as they go along.

 

Sculling boats do a similar thing but they tend not to be moving quite as fast and not so close so the waves calm down a bit.

 

I reserve the right to be totally wrong about all of the above

[john6767]

Rowers do the same as canoes, even on a big river like the Severn at Worcester. I presume it is to do with the frequency of the waves that they set up?

[magnetman]

 

 

I think WJM is the forum's kayak expert

Rowers do the same as canoes, even on a big river like the Severn at Worcester. I presume it is to do with the frequency of the waves that they set up?

Yes and they do go a lot faster than canal boats

[brassedoff]

Bow and Paddle water movement.

 

I Kayak on my own but tend to go slow, some give it beans some dont.

[zenataomm]

I think it's because the energy is near the surface of the water in comparison to a boat's propeller.

Also the disturbed water bounces off the bank both sides and these waves cross each other, often repeatedly.

 

Frequencies and harmonics can set up a pattern that prolongs the wave.

 

Or it could be the flux of The Earth .....

Or maybe they're like swans and under the water it's all chaos.

[OldGoat]

I was screamed at by a resident on the city end of the Coventry last year - and my response was very intemperate.

We had passed him at reasonable speed, but a pair of canoers had rocketed past in the opposite direction moments before. I didn't have the presence of mind to say 'not me guv' (but he wouldn't have accepted that anyway).

 

So yes they can and do create a lot of wash. In square law proportions too....

[mark99]

I think there may be something in the harmonics.

 

Each successive wave hitting the stationary boat just at the right time to rock it a bit further for a short while. (Think mini San Francisco bridge failure) Whilst a steel vessel "sucks, drags and draws".

[brassedoff]

I went on the cheshire ring with my Mecury 15hp Inflatable, even going at tick over it caused way too much wash.

 

it emptied the canal behind me could not go any slower, sold it for that reason.

 

and yep i was legal and had a cert/insurance lol

Edited July 28, 2015 by brassedoff

[Ray T]

I think there may be something in the harmonics.

 

Each successive wave hitting the stationary boat just at the right time to rock it a bit further for a short while. (Think mini San Francisco bridge failure) Whilst a steel vessel "sucks, drags and draws".

 

Isn't that what a peer of the Realm has done recently?

[mark99]

 

Isn't that what a peer of the Realm has done recently?

 

And sniffs

[magnetman]

I went on the cheshire ring with my Mecury 15hp Inflatable, even going at tick over it caused way too much wash.

 

it emptied the canal behind me could not go any slower, sold it for that reason.

 

and yep i was legal and had a cert/insurance lol

Were you in a 10ft speedboat?

[brassedoff]

Were you in a 10ft speedboat?

No lol

 

It was a 3.5 inflatable Zodiac about oow 8 years ago.

 

we did not have a water skier either, he fell off lol

 

i only used it twice on the canal.

Edited July 28, 2015 by brassedoff

[Bettie Boo]

Thanks everyone - some / most of the replies make sense to me, or better to say I kinda get the gist of it.

 

I think there may be something in the harmonics.

 

Each successive wave hitting the stationary boat just at the right time to rock it a bit further for a short while. (Think mini San Francisco bridge failure) Whilst a steel vessel "sucks, drags and draws".

 

This ^^^ I understand - was able to form a picture in my mind and now have a much better understanding - thanx Mark

[Alan Saunders]

Even a canoe moving at or near its maximum hull speed will produce a wave that will rock your boat. Several overtaking canoes may rock it more. For anyone used to boating on the sea, even in a harbour, these are only ripples, not really waves.

 

As the OP, 'BB' suggests, it is not a problem! If your boat does not move it is aground!

 

Alan

[Scholar Gypsy]

I think this is a surface wave effect - ie the kayak/speedboat makes waves on the surface which cause you to bounce up and down a bit vertically, but are unlikely to move you much in a horizontal direction. The water moves up and down only (in the main).

 

By contrast a passing heavy boat on tickover (see this thread) is unlikely to generate any significant surface waves. But the effect of moving X tonnes of water from in front of you to behind you, and the propellor drawing water in from the sides, is actually moving quite a lot of water around from one place to another. So this is quite likely to move you in a horizontal direction (normally forwards/backwards) which can cause problems with mooring pins etc.

[Athy]

I think this is a surface wave effect - ie the kayak/speedboat makes waves on the surface which cause you to bounce up and down a bit vertically, but are unlikely to move you much in a horizontal direction. The water moves up and down only (in the main).

 

 

Yes, this is what we find at our Cropredy mooring when the regular Saturday and Sunday morning canoe club flotilla goes past. Thanks for the lucid explanation, which even a non-techie like me can understand.

[Bettie Boo]

I think this is a surface wave effect - ie the kayak/speedboat makes waves on the surface which cause you to bounce up and down a bit vertically, but are unlikely to move you much in a horizontal direction. The water moves up and down only (in the main).

 

By contrast a passing heavy boat on tickover (see this thread) is unlikely to generate any significant surface waves. But the effect of moving X tonnes of water from in front of you to behind you, and the propellor drawing water in from the sides, is actually moving quite a lot of water around from one place to another. So this is quite likely to move you in a horizontal direction (normally forwards/backwards) which can cause problems with mooring pins etc.

 

Yes, another clear explanation ^^ for someone who doesn't have the best understanding (none really) of physics - Thank You

[FadeToScarlet]

I think this is a surface wave effect - ie the kayak/speedboat makes waves on the surface which cause you to bounce up and down a bit vertically, but are unlikely to move you much in a horizontal direction. The water moves up and down only (in the main).

 

By contrast a passing heavy boat on tickover (see this thread) is unlikely to generate any significant surface waves. But the effect of moving X tonnes of water from in front of you to behind you, and the propellor drawing water in from the sides, is actually moving quite a lot of water around from one place to another. So this is quite likely to move you in a horizontal direction (normally forwards/backwards) which can cause problems with mooring pins etc.

Exactly. Thinking about rowing boats, when the power is put on during the drive phase of the stroke, the bows of the rowing boat lift as it accelerates through the water. At the finish where the blades are extracted, the boat sits down again. Then you have, if it's an eight, 75kg of boat, 60 or so kg of coxswain, and about 650kg of rowers' weight lifting and dropping, setting up a vertical displacement.

[WJM]

It puzzles me too - the effort required to rock a narrowboat while standing on the bank is enormous - yet it seems that I can glide effortlessly past in a canoe or kayak and twenty tonnes of narrowboat is thrown about with a mere flick of a paddle.

[bizzard]

And Kayaks roll slightly from side to side on every paddle stroke made by the paddler that squashes water out alternately on each side which doesn't help. Squish, squash, squish, squash, squish, squash, squish, squash.