Boat Building Forum

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Re: The Long Boat Myth
By:Johne
Date: 6/11/2009, 12:08 pm
In Response To: The Long Boat Myth *LINK* *Pic* (Kudzu)

: Clearly the longer hulls are faster. At 8 lbs of resistance the 21 ft boat
: would be at least .5 mph faster than the 15 foot version. Meaning for the
: same amount of effort from the paddler would go faster in the long boat.
: So long boats are faster. Well, actually they have more speed potential if
: you have the horsepower to power the boat.

: At 2 lb of resistance the 15' boat is approximately .4 mph faster than the
: 21' boat. Meaning if you paddled for 2 hours that would put you almost a
: mile further down the river for the same amount of effort.

What you are seeing is the difference between wave making resistance and wetted surface resistance. Wetted surface is greater for the longer hull for the same displacement. The resistance of wetted surface is simply area x v squared (not really, but close enough for this discussion). So more area means more drag. The wave/pressure drag part is a function of Froude number and will be lower for the longer hull. At lower speeds this is a smaller part of the overall drag and so the lower wetted area is the key. At higher speeds it is the other way around, so the longer hull has less resistance.

Messages In This Thread

Skin-on-Frame: Fast, Playful SOF *Pic*
Michael Collins -- 6/8/2009, 11:10 pm
Re: Skin-on-Frame: Fast, Playful SOF
Aaron H -- 6/9/2009, 3:36 pm
Re: Skin-on-Frame: Fast, Playful SOF
Michael Collins -- 6/9/2009, 10:39 pm
Re: Skin-on-Frame: Fast, Playful SOF
Aaron H -- 6/10/2009, 6:11 pm
Re: Skin-on-Frame: Fast, Playful SOF
Brian Scaborough -- 6/10/2009, 10:21 am
Re: Skin-on-Frame: Fast, Playful SOF
John D. -- 6/10/2009, 3:02 pm
The Long Boat Myth *LINK* *Pic*
Kudzu -- 6/9/2009, 7:43 pm
Re: The Long Boat Myth
Mike Savage -- 6/11/2009, 7:01 pm
Re: The Long Boat Myth
Johne -- 6/11/2009, 12:08 pm
Re: The Long Boat Myth
Michael -- 6/11/2009, 10:23 am
Re: The Long Boat Myth *Pic*
Allan -- 6/11/2009, 3:54 am
Re: The Long Boat Myth
Bill Hamm -- 6/11/2009, 9:50 am
Re: The Long Boat Myth
Kudzu -- 6/11/2009, 11:56 am
Re: The Long Boat Myth
Michael Collins -- 6/11/2009, 1:58 pm
Re: The Long Boat Myth
Kudzu -- 6/11/2009, 5:33 pm
Re: The Long Boat Myth
Bill Hamm -- 6/13/2009, 1:23 am
Re: The Long Boat Myth
Terry Haines -- 6/18/2009, 11:45 pm
Re: The Long Boat Myth
Bill Hamm -- 6/19/2009, 11:39 am
Re: The Long Boat Myth
John F Monroe -- 6/24/2009, 5:42 am
Re: The Long Boat Myth
Terry Haines -- 6/19/2009, 6:33 pm
Re: The Long Boat Myth
Bill Hamm -- 6/11/2009, 1:26 pm
Re: The Long Boat Myth
Kudzu -- 6/11/2009, 7:42 am
Re: The Long Boat Myth
Allan -- 6/11/2009, 8:02 am
Re: The Long Boat Myth
Kudzu -- 6/11/2009, 9:19 am
Re: The Long Boat Myth
West -- 6/11/2009, 4:23 am
Re: The Long Boat Myth
Allan -- 6/11/2009, 7:45 am
Re: The Long Boat Myth
Ken Brunton -- 6/10/2009, 11:13 am
Re: The Long Boat Myth
Kudzu -- 6/10/2009, 1:40 pm
Re: The Long Boat Myth
Michael Collins -- 6/10/2009, 2:16 pm
Re: The Long Boat Myth
Kudzu -- 6/10/2009, 7:52 pm
Re: The Long Boat Myth
Bill Hamm -- 6/10/2009, 3:44 pm
Re: The Long Boat Myth
Michael Collins -- 6/9/2009, 10:26 pm
Re: The Long Boat Myth
Kudzu -- 6/10/2009, 8:33 am
Re: The Long Boat Myth
Nick Schade - Guillemot Kayaks -- 6/10/2009, 8:49 am
Re: The Long Boat Myth
Kudzu -- 6/10/2009, 1:08 pm
Re: The Long Boat Myth
Nick Schade - Guillemot Kayaks -- 6/11/2009, 10:35 am
Hey Nick
Kudzu -- 6/12/2009, 10:18 am
Single change??
Allan -- 6/12/2009, 6:47 pm
Re: The Long Boat Myth
Kudzu -- 6/11/2009, 12:04 pm
Re: The Long Boat Myth
Glen Smith -- 6/9/2009, 8:16 pm
Re: The Long Boat Myth
Kudzu -- 6/10/2009, 8:17 am
Re: The Long Boat Myth
Nick Schade - Guillemot Kayaks -- 6/10/2009, 8:57 am
Re: Skin-on-Frame: Fast, Playful SOF
Bill Hamm -- 6/9/2009, 1:15 am
Re: Skin-on-Frame: Fast, Playful SOF
Brian Scaborough -- 6/9/2009, 8:32 am
Re: Skin-on-Frame: Fast, Playful SOF
wwfloyd -- 6/10/2009, 7:47 pm
Re: Skin-on-Frame: Fast, Playful SOF
Bill Hamm -- 6/11/2009, 1:00 am
Re: Skin-on-Frame: Fast, Playful SOF *LINK* *Pic*
Tom Yost -- 6/9/2009, 10:24 am
Re: Skin-on-Frame: Fast, Playful SOF
Bill Hamm -- 6/9/2009, 8:28 pm
Re: Skin-on-Frame: Fast, Playful SOF
Tom Yost -- 6/10/2009, 12:41 am
LMAO!
Robert N Pruden -- 6/9/2009, 2:43 pm
Re: LMAO! *Pic*
Tom Yost -- 6/9/2009, 6:13 pm
Re: LMAO!
Bill Hamm -- 6/9/2009, 8:30 pm
Re: Skin-on-Frame: Fast, Playful SOF
Brian Scaborough -- 6/9/2009, 10:40 am
Re: Skin-on-Frame: Fast, Playful SOF
Michael Collins -- 6/9/2009, 11:11 pm
Re: Skin-on-Frame: Fast, Playful SOF
Brian Scaborough -- 6/10/2009, 1:00 pm
Balancing Gear
Michael Collins -- 6/10/2009, 2:01 pm
Re: Balancing Gear
Bill Hamm -- 6/10/2009, 3:40 pm
Re: Balancing Gear *LINK*
Brian Scaborough -- 6/10/2009, 2:27 pm
Re: Skin-on-Frame: Fast, Playful SOF *Pic*
Tom Yost -- 6/9/2009, 11:01 am
I've done that, too, but only with the Guinness.
Robert N Pruden -- 6/9/2009, 2:46 pm
Re: Skin-on-Frame: Fast, Playful SOF
Brian Scarborough -- 6/9/2009, 12:00 am
Rider, Ranger?
Michael Collins -- 6/9/2009, 11:07 pm
Re: Rider, Ranger?
Bill Hamm -- 6/10/2009, 2:27 am