Boat waves - how many?

DickR · 04-26-2011, 08:52 AM

With the water quiet as a mill pond, and almost no boat traffic midweek this time of year, it's interesting to see wave patterns on the water. I've noticed that a fast moving boat, on plane, seems to make relatively few waves, and of course they tend to come in almost parallel to shore. The low angle of the wave relative to boat path of course is due the boat's speed.

This morning I noticed a small work boat type of craft moving slowly through a thin fog. Looking out over the water, each wave was identified by the change in reflected light at the low angle. It seemed that there were dozens of waves being left by the slow moving boat.

Wave speed, of course, is simply a matter of water depth and density (fresh vs salt). But can anyone shed some light on what determines how many waves a boat will make?

[Moderator: I ought to have posted this in General Discussion]

crowsnest · 04-26-2011, 09:22 AM

Winnipesaukee · 04-26-2011, 09:24 AM

but I think in theory a boat would make an infinite number of wakes. They would become smaller until they become microscopic in size...?

Onshore · 04-26-2011, 11:05 AM

http://www.pianc.org/downloads/dwa/W..._DPWApaper.pdf

NoBozo · 04-26-2011, 12:16 PM

An even more interesting question would be this. Does a fast moving Nuclear Submarine cruising at say 25 knots @ 100 feet (depth) make a wake on the surface..and what would it look like...?

NB

http://www.fotosearch.com/photos-images/boat-wake.html

jrc · 04-26-2011, 12:17 PM

Great post, we need a link to the tool, could be a lot of fun. Who knew that Austrailia would develop such a tool, I didn't think they had any inland waterways.

Onshore · 04-26-2011, 01:23 PM

If the tool is available as open source software and I find it, I will post a link. Often times modeling program of that nature need to purchased.

Rattlesnake Guy · 04-26-2011, 06:28 PM

I have done a lot of personal research on the subject. By which I mean sitting and watching waves travel from stern to shore. The height of the wave diminishes but the number of waves increases. One of the benefits of the 150 foot from shore rule is that the size of the waves is smaller. The amount of total energy may be similar but each wave packs less punch.

---W---- ----WV---- ----WW---- ----www--- ----wwww---

camp guy · 04-26-2011, 08:33 PM

This is THE PERFECT post for Acres Per Second. Basically, he hates waves, and the more there are the more he hates them; also, he is a scientist, so he can postulate, extrapolate, hypothecate, to his heart's content solving this question.

AB_Monterey · 04-26-2011, 10:24 PM

We wave to all boats.

trfour · 04-27-2011, 01:38 AM

Quote:

Originally Posted by AB_Monterey

We wave to all boats.

Even when the Lake Winnipesaukee waves get flattened out!
http://www.winnipesaukee.com/photopo...hp?photo=17302
The waves here are spontaneous!

Terry
________________________

tis · 04-27-2011, 06:22 AM

Quote:

Originally Posted by camp guy

This is THE PERFECT post for Acres Per Second. Basically, he hates waves, and the more there are the more he hates them; also, he is a scientist, so he can postulate, extrapolate, hypothecate, to his heart's content solving this question.

You are so right! Where IS he???

SIKSUKR · 04-27-2011, 02:02 PM

I'm going to waive my right to post an answer.

Rusty · 04-27-2011, 02:21 PM

Quote:

Originally Posted by camp guy

This is THE PERFECT post for Acres Per Second. Basically, he hates waves, and the more there are the more he hates them; also, he is a scientist, so he can postulate, extrapolate, hypothecate, to his heart's content solving this question.

You forgot the most important one......"manipulate"

ApS · 04-29-2011, 05:34 AM

Quote:

Originally Posted by camp guy

This is THE PERFECT post for Acres Per Second. Basically, he hates waves,
and the more there are the more he hates them; also, he is a scientist, so
he can postulate, extrapolate, hypothecate, to his heart's content solving
this question.

Quote:

Originally Posted by tis

You are so right! Where IS he???

My old computer, which is no longer "supported by anybody" has to be fired
up, and it's even slower than usual—no longer supported by any anti-virus
protection. My old Outlook Express is filled up and jammed. With my new computer, I'm presently aground in some kind of "Winnipesaukee queue".

I really don't know the physics of waves—but do have some practical experience with water's waves—Winnipesaukee's in particular.

It is usual to see an average of seven waves from each boat—each side. Pontoon boats make the smallest wake of all powerboats—with the exception of the rarer tunnel-hulls. Flat-bottom boats make small waves, while "deep-V" make the biggest. Heavier boats make the largest waves while trying to plane.

I've noticed that the third wave is always the one that comes over the bow. I learned most-speedily, when the water is cold.

From aircraft, wakes can be seen to travel outwards indefinitely, to reach
the point at which my geometry teacher enjoyed calling, "asymptotic-nothingness".

I agree with R-Guy that the 150' rule has saved many small craft from being swamped. However, with my choice of boat (Carver)—and my choice in the manner of loading it (everybody aft)—havoc can be created even among
cruisers sitting at anchor.

tis · 04-29-2011, 07:00 AM

THERE you are, ACRES!!

04-26-2011, 08:52 AM	#1
DickR Senior Member Join Date: Apr 2008 Location: Moultonborough Posts: 735 Thanks: 4 Thanked 254 Times in 166 Posts	Boat waves - how many? With the water quiet as a mill pond, and almost no boat traffic midweek this time of year, it's interesting to see wave patterns on the water. I've noticed that a fast moving boat, on plane, seems to make relatively few waves, and of course they tend to come in almost parallel to shore. The low angle of the wave relative to boat path of course is due the boat's speed. This morning I noticed a small work boat type of craft moving slowly through a thin fog. Looking out over the water, each wave was identified by the change in reflected light at the low angle. It seemed that there were dozens of waves being left by the slow moving boat. Wave speed, of course, is simply a matter of water depth and density (fresh vs salt). But can anyone shed some light on what determines how many waves a boat will make? [Moderator: I ought to have posted this in General Discussion] Last edited by DickR; 04-26-2011 at 09:16 AM. Reason: Wrong subforum

04-26-2011, 09:24 AM	#3
Winnipesaukee Senior Member Join Date: Feb 2007 Posts: 233 Thanks: 14 Thanked 16 Times in 12 Posts	I'm no scientist... but I think in theory a boat would make an infinite number of wakes. They would become smaller until they become microscopic in size...? __________________ Sail fast, live slow!

04-26-2011, 08:33 PM	#9
camp guy Senior Member Join Date: Apr 2004 Location: formerly Winter Harbor, still Wolfeboro Posts: 1,134 Thanks: 284 Thanked 480 Times in 271 Posts	Boat waves - how many? This is THE PERFECT post for Acres Per Second. Basically, he hates waves, and the more there are the more he hates them; also, he is a scientist, so he can postulate, extrapolate, hypothecate, to his heart's content solving this question.

04-27-2011, 02:02 PM	#13
SIKSUKR Senior Member Join Date: Apr 2004 Posts: 5,075 Thanks: 215 Thanked 903 Times in 509 Posts	I'm going to waive my right to post an answer. __________________ SIKSUKR

04-26-2011, 09:22 AM	#2
crowsnest Senior Member Join Date: Sep 2010 Location: Whitman Ma / Weirs Beach Posts: 94 Thanks: 42 Thanked 25 Times in 19 Posts

04-26-2011, 11:05 AM	#4
Onshore Senior Member Join Date: Apr 2004 Posts: 500 Thanks: 12 Thanked 400 Times in 143 Posts	http://www.pianc.org/downloads/dwa/W..._DPWApaper.pdf

The Following 2 Users Say Thank You to Onshore For This Useful Post:
Jonas Pilot (04-26-2011), Lakegeezer (04-26-2011)

04-26-2011, 12:16 PM	#5
NoBozo Senior Member Join Date: Jun 2008 Location: Portsmouth. RI Posts: 2,231 Thanks: 400 Thanked 460 Times in 308 Posts	An even more interesting question would be this. Does a fast moving Nuclear Submarine cruising at say 25 knots @ 100 feet (depth) make a wake on the surface..and what would it look like...? NB http://www.fotosearch.com/photos-images/boat-wake.html

04-26-2011, 12:17 PM	#6
jrc Senior Member Join Date: Apr 2004 Location: NH Posts: 2,689 Thanks: 33 Thanked 439 Times in 249 Posts	Great post, we need a link to the tool, could be a lot of fun. Who knew that Austrailia would develop such a tool, I didn't think they had any inland waterways.

04-26-2011, 01:23 PM	#7
Onshore Senior Member Join Date: Apr 2004 Posts: 500 Thanks: 12 Thanked 400 Times in 143 Posts	If the tool is available as open source software and I find it, I will post a link. Often times modeling program of that nature need to purchased.

04-26-2011, 06:28 PM	#8
Rattlesnake Guy Senior Member Join Date: Sep 2004 Posts: 1,254 Thanks: 423 Thanked 366 Times in 175 Posts	I have done a lot of personal research on the subject. By which I mean sitting and watching waves travel from stern to shore. The height of the wave diminishes but the number of waves increases. One of the benefits of the 150 foot from shore rule is that the size of the waves is smaller. The amount of total energy may be similar but each wave packs less punch. ---W---- ----WV---- ----WW---- ----www--- ----wwww---

The Following User Says Thank You to Rattlesnake Guy For This Useful Post:
Sunset Bob (04-27-2011)

04-26-2011, 10:24 PM	#10
AB_Monterey Senior Member Join Date: Aug 2008 Location: Alton Bay Posts: 293 Thanks: 86 Thanked 78 Times in 49 Posts	We wave to all boats.

The Following 2 Users Say Thank You to AB_Monterey For This Useful Post:
Smith Point (04-27-2011), Sunset Bob (04-27-2011)

04-29-2011, 07:00 AM	#16
tis Senior Member Join Date: Jan 2006 Posts: 6,405 Thanks: 719 Thanked 1,379 Times in 955 Posts	THERE you are, ACRES!!

The Following User Says Thank You to tis For This Useful Post:
ApS (06-13-2011)