Ken Boyd's Toy

[kenboyd]

1997 Hawaiian made 12' Sport C tunnel boat. Driver/Owner Ken Boyd. 51.9 mph @ 5100 rpm, Driver handheld GPS. Ron Hill 4 blade cleaver, 12 5/8" X 30". Stock 1989 70hp Evinrude powerhead. Gear ratio 12/29, 1988 60hp gearcase. Big Foot low water pick up. 20" mid-section. http://www.youtube.com/watch?v=dqtSZBS5HzE

[Roy Hodges]

1997 Hawaiian made 12' Sport C tunnel boat. Driver/Owner Ken Boyd. 51.9 mph @ 5100 rpm, Driver handheld GPS. Ron Hill 4 blade cleaver, 12 5/8" X 30". Stock 1989 70hp Evinrude powerhead. Gear ratio 12/29, 1988 60hp gearcase. Big Foot low water pick up. 20" mid-section. http://www.youtube.com/watch?v=dqtSZBS5HzE............................... ............................................
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I think you need to get a short (15") tower housing . I also think maybe you are NOT running the unit SURFACING . you are about 20 mph slow . Only the bottom blade should be in the water ,or at the most down one notch on your transom bracket ( 5/8" ) . I mean only 5/8" of the bottom of the gear case in the water . Your low speed and too low rpm/s tell me that . But, if you set it up for max speed , it will probably be dangerous to turn , but a good straighta way speed.

[kenboyd]

I think you need to get a short (15") tower housing . I also think maybe you are NOT running the unit SURFACING . you are about 20 mph slow . Only the bottom blade should be in the water ,or at the most down one notch on your transom bracket ( 5/8" ) . I mean only 5/8" of the bottom of the gear case in the water . Your low speed and too low rpm/s tell me that . But, if you set it up for max speed , it will probably be dangerous to turn , but a good straighta way speed.


Roy,
Thank you for the information.:) As finances allow, I will be gravitating towards a 15 inch midsection (to lower my center of gravity), and a 1.87 (15/28) gear ratio and new props, to increase my top speed, and, and, and,..... The list goes on .....
Right now I'm swapping my 60 hp gearcase (that I broke), for a 70 hp gearcase (that I had laying around). The 70 hp gearcase has a deeper skeg, which will help control the side slip that I sometimes get, when I'm flying the hull.
I will be using 2.416 (12/29) gearing, because that's what I have available right now. This will limit my speed, as it did on my 60 hp gearcase, but it will help keep me in a safe range, since I'm learning how to drive this boat.
Unless the weather is really bad, I usually test about two hours every morning, and sometimes in the evenings.
I've raised the transom 4 inches, so that when I am flying the hull, the propeller is high enough to run on the surface and still maintain a good thrust angle, as well as hull angle of attack.
When conditions are right and I'm flying the hull, my prop is about half in the water may be slightly less. 5/8" would be a bit shallow from my water pick up.
I am developing a dialogue with Ron Hill, about building a five blade prop, that he suggested I run. I'll be reducing my pitch from 30 inches (which was too much for my engine) to 27 inches. My logic is that reducing the pitch that much should bring my rpm up enough to make the engine little more efficient. An increase in top speed should also come, but still in the 50 mph range. Basic stuff.
In the meantime, I will be enjoying what I have.
Ken

[Roy Hodges]

how deep are your sponsons? on my old sport E boat i ran the transom height 23&3/8" . That was with a 15" tower housing . it got water fine . My sponsons were about 7" deep at transom. I had no low water pickup, not legal. I had stock nitro lower unit . 15/23 gears. it ran best with a V-4 race prop, 24" pitch , borrowed . Was worked over by DAH ( DON HENRICH ). for kilos ,i would have run 24" transom height , in straightaway, it was a rocket. only time i went to kilos , it( water) was too rough to try . fast enough to fly ,at speed . it took about 100 yards to settle down into water , after chopping the throttle.

[kenboyd]

how deep are your sponsons? on my old sport E boat i ran the transom height 23&3/8" . That was with a 15" tower housing . it got water fine . My sponsons were about 7" deep at transom. I had no low water pickup, not legal. I had stock nitro lower unit . 15/23 gears. it ran best with a V-4 race prop, 24" pitch , borrowed . Was worked over by DAH ( DON HENRICH ). for kilos ,i would have run 24" transom height , in straightaway, it was a rocket. only time i went to kilos , it( water) was too rough to try . fast enough to fly ,at speed . it took about 100 yards to settle down into water , after chopping the throttle.


Roy,
My sponsons are also 7". The transom height is 23", the engine is an inch above that. The transom is set back 15" at the top angling in to 8" at the bottom.
I forgot to mention that when my boat had a 40 hp Nissan on it without a low water pickup, I burned up the motor by sucking in too much air, while going through boat wakes.
How long was your sport E, and what type of engine did it have?
Ken

[Roy Hodges]

[QUOTE=kenboyd;69109]Roy,
My sponsons are also 7". The transom height is 23", the engine is an inch above that. The transom is set back 15" at the top angling in to 8" at the bottom.
I forgot to mention that when my boat had a 40 hp Nissan on it without a low water pickup, I burned up the motor by sucking in too much air, while going through boat wakes.
How long was your sport E, and what type of engine did it have?
Ken............................................... .................................................. ...............................
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my boat was 13'10" . It had a 1975 - 75 horse short shaft Evinrude HUSTLER (same as Johnson STINGER ). one off, had originally been built for "R" class . OPC.

[bbgun]

[QUOTE=kenboyd;69109]Roy,
My sponsons are also 7". The transom height is 23", the engine is an inch above that. The transom is set back 15" at the top angling in to 8" at the bottom.
I forgot to mention that when my boat had a 40 hp Nissan on it without a low water pickup, I burned up the motor by sucking in too much air, while going through boat wakes.
How long was your sport E, and what type of engine did it have?
Ken............................................... .................................................. ...............................
.................................................. .................................................. ..................................
my boat was 13'10" . It had a 1975 - 75 horse short shaft Evinrude HUSTLER (same as Johnson STINGER ). one off, had originally been built for "R" class . OPC.

Are you guys aware if a 75 evinrude sprint is the same as a 75 hustler? I am told they are the same motor?

[Roy Hodges]

[QUOTE=bbgun;71554][QUOTE=Roy Hodges;69115]

Are you guys aware if a 75 evinrude sprint is the same as a 75 hustler? I am told they are the same motor?............................................ .................................................. ...............
.................................................. .................................................. .................................I don't remember ,for sure, but I think the Sprint was a 2 cylinder 50 horsepower.

[bbgun]

[QUOTE=bbgun;71554][QUOTE=Roy Hodges;69115]

Are you guys aware if a 75 evinrude sprint is the same as a 75 hustler? I am told they are the same motor?............................................ .................................................. ...............
.................................................. .................................................. .................................I don't remember ,for sure, but I think the Sprint was a 2 cylinder 50 horsepower.

Here is a link to it

http://forums.screamandfly.com/forums/showthread.php?p=1623355#post1623355