do dolphins slow you down

dylanwinter

dylanwinter

Well-Known Member
Joined
28 Mar 2005
Messages
12,954
Location
Buckingham
www.keepturningleft.co.uk
they are rising your bow wave

so are they making it harder for the boat to create that wave

when they are hitching a ride are they slowing you down?

water is incompressible so I assume they are creating a tiny amount of extra back pressure on the bow

Dylan
 
Last edited:
The world stopped as far as I was concerned.Our first time close encounter caught on film by Sea Rush
View attachment 35059

You also risk chucking your expensive smart phone in the water when one unexpectadly jumps clear out of the water right in front of you!

If I knew how to link to a video on facebook I could show a video of the beautiful creature in the still.
 
No, there is no feedback from where the dolphin rides the wave to the boat that is making the wave. It is taking energy out of the wave; energy your boat already put into it, so I guess it (very slightly) reduces your bow-wave.

Perhaps that's the answer to excessive wash - get trained dolphins to ride the wave, and reduce it to manageable proportions :D
 
[video]https://www.facebook.com/video/embed?video_id=654239561283063" width="1280" height="720" frameborder="0"[/video]

Don't know if this will work, well, it's working for me now & is set to public, so you should be able to click on it.

But yes they don't half slow you down as you completely forget about sail settings & helm.
 
Last edited:
In theory, any interference with the smooth flow will affect and impact the boat. In this case the dolphin, as it travelling close to the boat, will exert a force wave against the boat, as well as creating additional turbulence.

Dammed dolphins, now I know why my Macwester is so slow and perhaps the notorious leeway is caused by shoals of mackerel catching up with the boat, because of the dolphin effect, and thus pushing me sideways. Everything is clear now.
 
Last edited:
I once had a solitary Bottlenose accompany me from off the Pembroke coast all the way to to the tip of Land's End. He started off by lying with his shoulder (do dolphins have shoulders?) against the hull just aft of amidships. I assuming he was taking advantage of the laminar flow and just being towed along...which, I'd imagine, did slow me a fraction. But well worth it. He occasionally toddled off to investigate other boats, but always returned, before abruptly peeling off at Land's End: the end of his 'patch'? He looked quite battleworn, and I assume he was an old male, kicked out of his pod by a younger one.

We've exchanged Christmas cards ever since.
 
sailorman said:
Yes coz you stop paying attention & watch / film them
Click to expand...

Oh I am pleased I'm not the only one.

At the bottom of the West Kyle (Ardlamont point) there is a port hand marker which has a resident Dolphin. I stopped and cruised around the can last Saturday and watched her display around Little Ship.

Yesterday I once again decided to see her again, I never get tired of watching Dolphins. This time however there were two..... She has had a pup over the weekend which she kept bringing over to the boat, I assume showing off.

Brilliant to see but bloody difficult to photograph, I have about a dozen photos of water around the buoy.

Tom.

Don't forget to turn off the depth sounder if you are watching them.
 
JumbleDuck said:
<cough>Froude number less than 1<cough>

Yrs with yet more irritating pedantry

JumbleDuck
Click to expand...

Umm, could you amplify on this cryptic (to me anyway) remark? The boat will be a displacement hull, else dolphins won't ride a bow wave. So the Froude number for the boat will almost certainly be much less than 1 - probably 0.3 (assuming, among the several definitions of Froude number, that you mean Fnum = U / sqrt(g . Lwl), and use SI units.

EDIT. I think I get it - sorry, was perhaps a bit slow. I think you meant that since the bow wave velocity is faster than the boat's - the rough equivalent of subsonic flight -then it's not strictly true that interference with the bow wave which has left the boat can not affect the boat?
 
Last edited:
Depends on the Dolphins

These ones will.

Well someone was bound to say it.........
 
Last edited:
You must log in or register to reply here.

Share this page

Top