De 23 Performance

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johnscott
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De 23 Performance

Post by johnscott » Thu May 29, 2008 1:28 pm

Hi all
I am starting my de23 in the fall. I am anxious to know how she performs. Has anyone got one in the water? I was looking at a c-dory22 a production boat that is similar in a boat mag. Looks good!
Cheers
John



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jacquesmm
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Post by jacquesmm » Thu May 29, 2008 2:15 pm

Keep in mind that the figures I post on the study plans are for the designed displacement. Mots of the DE23/25 I have seen were built very heavy, loaded with more equipment than what I planned for and as such require much more HP.

All boats of the same hull shape and same weight go at about the same speed. It doesn't matter if they are wood or fiberglass, mass produced or built by an amateur.

Dave Gerr explains that in his propeller book and in another one. It's called the Crouch formula.
Vk = C /SQRT (Displ/SHP)

where
Vk = speed in knots (not mph)
C = constant factor
Displ = displacement in lbs
SHP = shaft horsepower

For the DE23/25, use a factor C of 150.

Reports from our builders show that the formula applied to our boats are accurate within 5%.
Jacques Mertens - Designer
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AmbitiousRookie
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Post by AmbitiousRookie » Thu May 29, 2008 5:58 pm

How do you determine the constant factor is that what the drag would be on the surface area of the boat? Just very curious not sure why formulas are so interesting to me.

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jacquesmm
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Post by jacquesmm » Fri May 30, 2008 9:10 am

That's experience.
After calculating and checking a large number of boats, you get a good feel for what coefficient applies to a certain hull type.

Dave Gerr, Lindsay Lord and other give guidelines in their books.
Jacques Mertens - Designer
http://bateau.com

johnscott
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Post by johnscott » Fri May 30, 2008 10:52 pm

Thanks Jacques
I was just curious to see some pictures of one in the water. I plan on 120 Hp. I only usuall do day trips and probably do not load it up much. I do seem to have a lot of gear I never use aboard my explorer though. I am looking for about 30- 35 mph. That gets me there safe then I use a kicker.
Here in BC it gets cold on the lake early so I need that cabin.
Cheers
John

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nort
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Post by nort » Sat May 31, 2008 11:38 am

Do a search for Woodbike. I know he has finished and his is on the water. I don't remember if he build the Novi or the Downeast, but performance should be close.

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woodbike
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Post by woodbike » Tue Jun 03, 2008 1:00 pm

with a 115 four stroke and 5 people ,50 gallons of fuel ,13 gallons of water ,a ahrd top and windshield etc...nice and flat water .we can get into the low 30's but into a head wind it fall's into the 20's

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Post by topwater » Tue Jun 03, 2008 3:47 pm

Woodbike how about some pic's of youre boat in action.
youre build made me fall in love with this hull.

johnscott
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Post by johnscott » Tue Jun 17, 2008 6:50 pm

Thanks Woodbike. I too would love to see some pictures of your boat. Don't know if I could find five brve souls to ride with me.

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Post by Bill_S » Mon Jun 23, 2008 11:13 pm

Hi-

I just posted a few pictures of my DE 23 that I launched last Friday. (on-the-water pix taken just prior to pulling it out yesterday)

I have done a limited amount of testing but am very pleased by initial results.

It is powered by a Yamaha 4-stoke 60 HP driving a 11.4 X 12 prop. Max GPS speed was little over 20 KTS with three aboard. However, I could not achieve the WOT recommended by Yamaha indicating I should reduce the size/pitch of the prop (max rpm was about 4800).

Rides well and gets on the plane around 12-13 kts. Stays on the plane down to around 8-9 kts. Very little change in pitch going to plane.
(notice waterline in the pix with speed <=5 kts or so).

I did not put any spray suppressors on the boat and it doesn't seem to need them. Do need to block the scuppers-fair amount of water sometimes.....

Questions?

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