# [EVDL] Electric Boat Hull Efficiency test



## EVDL List (Jul 27, 2007)

You may get interesting info my talking to sailboat
or even surfboard designers.
Especially about the efficiency and non-linear behavior
of it due to planing (lifting the hull up on a sheet of
water instead of pushing it through the water mass)
and the different hull shapes giving different areas
of optimum efficiency.

Since a windsurfer has only so much control over the
amount of power (only sail size & shape can be chosen for a
certain wind force) the other variable is the hull
shape of the board.

I remember that for low wind conditions the optimum
hull shape was typically the round, U- or long O-shaped 
and floating board type which had to be pushed
through the water, but could reach partial planing state
with relatively little wind and speed.
Higher wind force allowed an almost flat, slightly V-shaped
hull to be pushed at enough speed to reach full planing state
and at high wind force, it was even better to use boards
so flat, thin and small that they would not even stay afloat,
but were superior in speed and efficiency to everything else.

This all from my windsurfing days, which is more than 30 years ago...
Technology will definitely have developed since then so it is best
to swap experiences with a few hull designers.

Regards,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Mark Hanson
Sent: Monday, July 19, 2010 8:00 PM
To: [email protected]
Subject: [EVDL] Electric Boat Hull Efficiency test


Hi Folk's,



I went out again this week-end using the same E-drive 48V trolling motor
(largest Minnkota MK-101) on a U shaped hull 18' Suncatcher party barge.
Lats week-end was the O shaped hull party barge comparing to the V
shaped catamaran www.evalbum.com/1273 that Jerry Dycus built.



E-Cat V hull 8' x 18':

52A @ 5.1mph



O pontoon 21' also 1790 lbs in both directions:

55A @ 4.2mph



U pontoon 18' shaped hull also 1790 lbs (had more engine weight in rear)

60A @ 3.5mph



The E-Cat solar SunGo V shaped hull was 28% more efficient amps/mph than
the O hull (best comparison)



The E-Cat solar SunGo V shaped hull was 68% more efficient amps/mph than
the U hull party barge.



So I'll put the new inboard 16" x 16" prop drive on the E-Cat SunGo for
28% better efficiency than a standard O shaped pointy front party barge
hull.



(Sylvan looks to be the only one that make aluminum V shaped alum hulls
but a bit pricey now.)



have an Eboat day,

Mark

www.reevadiy.org 

_________________________________________________________________
The New Busy is not the too busy. Combine all your e-mail accounts with
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## EVDL List (Jul 27, 2007)

A Hull has a "Hull Speed", which is a function or the square root of the
water line length. What happens is a Hull pushes water ahead to create a
"Bow Wave", which cannot travel faster than a certain speed, as the boat
speeds up it catches up to this wave, planning speed is the speed at which
it overtakes this wave. To do this the boat has to travel up a "hill" which
is the Bow Wave, doing this may mean the prop has to push the boat up an
incline of up to 30 degrees, which takes huge power, at 30 degrees maybe 1/2
the weight of the boat in thrust, If the propulsion system cannot supply
this thrust it cannot get over the bow wave and it cannot plane. The "Hull
Speed" of my 7m sailboat is around 6 knots, it will do 5 knots with a 4hp
outboard at 1/4 throttle, but does not have enough power to plane. A well
designed Hull needs about 1Hp per ton below planning speed. 
The Catamaran hull is an attempt to get around this, at the ratio of
hull width to length decreases the angle of the hull to get over the bow
wave gets lower, and eventually can be disregarded, the hull does not plane
it just goes faster, so a cat hull is good for a boat that needs to go above
planning speeds but does not have a powerful motor. All else being equal,
the hull with less wetted area will need less power below Hull speed.
This is all from my dingy racing days.....




-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Cor van de Water
Sent: Tuesday, 20 July 2010 5:59 a.m.
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Electric Boat Hull Efficiency test

You may get interesting info my talking to sailboat
or even surfboard designers.
Especially about the efficiency and non-linear behavior
of it due to planing (lifting the hull up on a sheet of
water instead of pushing it through the water mass)
and the different hull shapes giving different areas
of optimum efficiency.

Since a windsurfer has only so much control over the
amount of power (only sail size & shape can be chosen for a
certain wind force) the other variable is the hull
shape of the board.

I remember that for low wind conditions the optimum
hull shape was typically the round, U- or long O-shaped 
and floating board type which had to be pushed
through the water, but could reach partial planing state
with relatively little wind and speed.
Higher wind force allowed an almost flat, slightly V-shaped
hull to be pushed at enough speed to reach full planing state
and at high wind force, it was even better to use boards
so flat, thin and small that they would not even stay afloat,
but were superior in speed and efficiency to everything else.

This all from my windsurfing days, which is more than 30 years ago...
Technology will definitely have developed since then so it is best
to swap experiences with a few hull designers.

Regards,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Mark Hanson
Sent: Monday, July 19, 2010 8:00 PM
To: [email protected]
Subject: [EVDL] Electric Boat Hull Efficiency test


Hi Folk's,



I went out again this week-end using the same E-drive 48V trolling motor
(largest Minnkota MK-101) on a U shaped hull 18' Suncatcher party barge.
Lats week-end was the O shaped hull party barge comparing to the V
shaped catamaran www.evalbum.com/1273 that Jerry Dycus built.



E-Cat V hull 8' x 18':

52A @ 5.1mph



O pontoon 21' also 1790 lbs in both directions:

55A @ 4.2mph



U pontoon 18' shaped hull also 1790 lbs (had more engine weight in rear)

60A @ 3.5mph



The E-Cat solar SunGo V shaped hull was 28% more efficient amps/mph than
the O hull (best comparison)



The E-Cat solar SunGo V shaped hull was 68% more efficient amps/mph than
the U hull party barge.



So I'll put the new inboard 16" x 16" prop drive on the E-Cat SunGo for
28% better efficiency than a standard O shaped pointy front party barge
hull.



(Sylvan looks to be the only one that make aluminum V shaped alum hulls
but a bit pricey now.)



have an Eboat day,

Mark

www.reevadiy.org 

_________________________________________________________________
The New Busy is not the too busy. Combine all your e-mail accounts with
Hotmail.
http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PI
D28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4
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## EVDL List (Jul 27, 2007)

Mark probably already knows this, but for those wanting electric boat
specific discussions and info, there's a 4000 member group online that
discusses all things electric on the water:
http://groups.yahoo.com/group/electricboats/
-myles twete, member and moderator of that group

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## EVDL List (Jul 27, 2007)

That gets me thinking, what about a hydrofoil?

In this case if you had say a V hull with some foils such that as speed increases it would lift the hull and reduce the width the
hull needs to displace.


> A Hull has a "Hull Speed", which is a function or the square root of the
> water line length. What happens is a Hull pushes water ahead to create a
> "Bow Wave", which cannot travel faster than a certain speed, as the boat
> speeds up it catches up to this wave, planning speed is the speed at which
> it overtakes this wave. To do this the boat has to travel up a "hill" which
> is the Bow Wave, doing this may mean the prop has to push the boat up an
> incline of up to 30 degrees, which takes huge power, at 30 degrees maybe 1/2
> the weight of the boat in thrust, If the propulsion system cannot supply
> this thrust it cannot get over the bow wave and it cannot plane. The "Hull
> Speed" of my 7m sailboat is around 6 knots, it will do 5 knots with a 4hp
> outboard at 1/4 throttle, but does not have enough power to plane. A well
> designed Hull needs about 1Hp per ton below planning speed. 
> The Catamaran hull is an attempt to get around this, at the ratio of
> hull width to length decreases the angle of the hull to get over the bow
> wave gets lower, and eventually can be disregarded, the hull does not plane
> it just goes faster, so a cat hull is good for a boat that needs to go above
> planning speeds but does not have a powerful motor. All else being equal,
> the hull with less wetted area will need less power below Hull speed.
> This is all from my dingy racing days.....


----------



## EVDL List (Jul 27, 2007)

It could work, depends what you trying to do.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Jeff Shanab
Sent: Wednesday, 21 July 2010 8:26 a.m.
To: [email protected]
Subject: Re: [EVDL] Electric Boat Hull Efficiency test

That gets me thinking, what about a hydrofoil?

In this case if you had say a V hull with some foils such that as speed
increases it would lift the hull and reduce the width the
hull needs to displace.


> A Hull has a "Hull Speed", which is a function or the square root of the
> water line length. What happens is a Hull pushes water ahead to create a
> "Bow Wave", which cannot travel faster than a certain speed, as the boat
> speeds up it catches up to this wave, planning speed is the speed at which
> it overtakes this wave. To do this the boat has to travel up a "hill"
which
> is the Bow Wave, doing this may mean the prop has to push the boat up an
> incline of up to 30 degrees, which takes huge power, at 30 degrees maybe
1/2
> the weight of the boat in thrust, If the propulsion system cannot supply
> this thrust it cannot get over the bow wave and it cannot plane. The "Hull
> Speed" of my 7m sailboat is around 6 knots, it will do 5 knots with a 4hp
> outboard at 1/4 throttle, but does not have enough power to plane. A well
> designed Hull needs about 1Hp per ton below planning speed. 
> The Catamaran hull is an attempt to get around this, at the ratio of
> hull width to length decreases the angle of the hull to get over the bow
> wave gets lower, and eventually can be disregarded, the hull does not
plane
> it just goes faster, so a cat hull is good for a boat that needs to go
above
> planning speeds but does not have a powerful motor. All else being equal,
> the hull with less wetted area will need less power below Hull speed.
> This is all from my dingy racing days.....


No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 9.0.851 / Virus Database: 271.1.1/3016 - Release Date: 07/20/10
18:36:00

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| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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