Top Speed Question

mytrojan · Post by **mytrojan** » Sun Sep 14, 2008 4:00 pm

I have a '71 Seavoyager 36 with twin mercs 270hp, wood hull. These are original and even though they are a bit tired, haven't had any issues with them. I cruise about 1800 and according to GPS about 8-10 mph. This is OK but as I get up over 2000, I notice vibrations and back off- don't want to push it.

I was wondering if anyone knows what the top speed of this boat was in its day. If I rebuilt the engines (the day is coming), what would be reasonable to expect for a top speed?

thanks.

rickalan35 · Post by **rickalan35** » Sun Sep 14, 2008 8:20 pm

My T. - Nice boat.

I wonder if those vibrations are prop related and not your powerplants.

1967 seavoyager · Post by **1967 seavoyager** » Sun Sep 14, 2008 10:10 pm

Last time i was in the water (2001) i got 29.5 mph at about 3500 rpm. shook & rattled real bad at full throttle. i get 10 mph at 1900 rpm.

http://www.photobucket.com/restless

jakevr · Post by **jakevr** » Mon Sep 15, 2008 6:55 am

make sure ur engines are aligned and shafts are straight and props are in good shape.

i was told my boat would run up to 4400 rpms top about 30 mph

mytrojan · Post by **mytrojan** » Tue Sep 16, 2008 1:11 pm

How can you tell if the engines are properly alligned and that the shaft is straight? It looks like it is, but is there some sort of measurement you can do- not sure how I check?

I can check the props this winter.

chucka · Post by **chucka** » Tue Sep 16, 2008 10:48 pm

Disconnect the shaft/transmission coupler and rotate the shaft relative to the transmission. The two flanges should remain parallel and concentric. You can check parallelism (angular in the 2nd article below) with feeler gauges between the flange faces at different angular positions. You can check concentricity (offset in the 2nd article below) by measuring runout with a dial indicator.

some related articles:
http://www.yachtsurvey.com/Alignment2.htm
http://www.state-electric.com/files/us- ... rt_one.pdf