bow lift needed

jolsen · 07-06-2009, 12:51 AM

Hi I am new to this forum. I have a dilema with my boat. I have installed a duramax diesel in my 79 sterling jet boat, that now sports an arneson 1720 inline drive and a crashbox. the boat is 19.5 feet I have a rolla 16.25x22 4blade cleaver not sure of the rake. The boat does 70mph at just over 3400rpm As far as I can tell this is around 1% slipage.all of this I am happy with but would like to try a 26p x 15 so that the prop won't throw the boat around also looking for a way to creat bow rise, because at this time the boat is wetted past past my toes and quite a handfull. Any insight would be greatly apreciated thanks

bbladesprops · 07-06-2009, 08:57 PM

If the g.r. is 1:1, your slip is low. Decreasing the diameter will help to lower the stern, which can help with bow lift.

Your rpm's could drop about 500.

Brett

jolsen · 07-07-2009, 12:43 AM

thanks for the info. the drive is 1-1 . also, do you know if rake will help or degrade performance ?

blackboat · 07-09-2009, 10:37 PM

More rake would help bow lift so would a round ear prop. arneson drives on a small boat are sometimes tough to get bow lift depending on angle of prop and drive

hallj · 09-29-2009, 12:55 PM

Make sure your trim tabs aren't dragging. A round ear prop would help. A horizontal fin on the skeg helps as well.

Jeff

seamy · 10-01-2009, 06:31 AM

Quote:

Originally Posted by hallj

Make sure your trim tabs aren't dragging. A round ear prop would help. A horizontal fin on the skeg helps as well.

Jeff

would a horizontal fin not create a lot of drag? very difficult to get any bow lift from a surface prop due to the fact that its only half in the water;hence cant get enough grip,or leverage to lift the bow.

hallj · 10-05-2009, 03:36 PM

Quote:

Originally Posted by seamy

would a horizontal fin not create a lot of drag? very difficult to get any bow lift from a surface prop due to the fact that its only half in the water;hence cant get enough grip,or leverage to lift the bow.

It's a lot less than dragging half of the hull through the water!

Dueclaws · 10-05-2009, 05:47 PM

I used a horizontal fin on an Arneson in a 19' Youngblood powered by a modified SBC. If there was drag from the fin it was negligble because the boat increased speed and stability.

seamy · 10-06-2009, 06:02 AM

Quote:

Originally Posted by Dueclaws

I used a horizontal fin on an Arneson in a 19' Youngblood powered by a modified SBC. If there was drag from the fin it was negligble because the boat increased speed and stability.

Have you any pics of the fin,and how much of an increase in speed did you see???

Dueclaws · 10-06-2009, 09:48 AM

Sorry, no photos of the fin and I don't remember the exact increase in speed, but the attitude of the boat was perfect.
The boat was built and sold some time ago. I have some video of the boat made during test runs, but need to convert it from VHS.