Propping a Sailfish - Rebel vs Viper

[onoahimahi]

Hi - I just "upgraded" my E-TEC props from 14 3/4" by 19" Vipers to 15 1/2" by 17" Rebels and tested them out yesterday. I put my "report" here:

http://www.etecownersgroup.com/post/Reb ... sh-6426775

The nutshell version based on this initial testing is slightly better low-speed performance in terms of RPM and slightly better fuel economy at fast cruising speeds. The WOT RPM went up by 150 to 5850 and the top speed dropped one kt to 48.5 MPH. Most economical cruising speed is 33 MPH at 4000 RPM and ~1.5 MPG. Load was medium to light with 125 gallons of fuel, full water and oil, some extra tools and gear but no passengers - just me.

I did the "plane on one engine" test with the Rebel prop and posted it on Youtube. I hit about 35 mph at 5100 RPM (with one engine out of the water) before backing down. The video is here:

http://www.youtube.com/watch?v=0PffCDl8WNM

My Sailfish is a 94 which has the shorter running surface - it should be easier (i.e, require less torque) to do this with a similarly loaded 98 or later Sailfish including the 282.

Some of the audio is difficult to hear but is explained in the video description. Also, there is a typo where I list the beam at 9'8" but I correct to 9'6" in the description.

-Scott

 

[seasick]

Something doesn't sound right.
If the fuel burn you stated was for both engines, at a speed of 33 MPH you travel r 33 miles devided by 1.5 or 22 miles per gallon. If the 1.5GPH was per motor that works out to 11 MPG.

 

[onoahimahi]

Something doesn't sound right.
If the fuel burn you stated was for both engines, at a speed of 33 MPH you travel r 33 miles devided by 1.5 or 22 miles per gallon. If the 1.5GPH was per motor that works out to 11 MPG.

Sorry - that was supposed to be 1.5 MPG not GPH - I fixed it above. The GPH was 22.

I took it out again tonight for a little cruise with my sister and my nieces. The girls insisted on sitting at the bow the whole time so I didn't want to cruise at 33 MPH. I was pleasantly surprised to find that I could plane more stably at slower speeds with the Rebels with the engines trimmed down a bit. For example, in the 3200 or 3300 range, I was able to plane stably at 18 or 20 kts. I'm not sure I could have done that with the Vipers.