Hi Brian,
Would you please let me know the diameter and pitch of your Campbell “Sailor” prop if you happen to have recorded it. Mine is 14x11. I’m not planning a change but am curious because I have not been able to reach hull speed at the maximum allowable revs of the W-27 during a trial. (flat water, no current, GPS me5asured speed). Also, I don’t get the 5 knots at 1800 revs that you do.
Thanks.
Joel Watt
N30U 258, Virgin Gorda,
Kingston, Ont
P S I see that you have traded in your Commodore 64.
Hello Joel, long time no see. Do you still have my duck?
The Kat is in the water and I did not record that information.
I have a W33 but that just gives me a bit more torque. The RPM range should be the same. I think 3000 should be the max although my tach shows 3300 RPM at full throttle but I’m just wasting fuel and creating one helluva moustache at that level as her big butt digs in.
I am unsure what the hull speed is on a 30, I have heard from 6.5 to 8 knots but I should imagine that it would be faster under sail as the centre of thrust is forward and much higher and keeps the nose down (longest waterline) while under power the bow tends to lift up and gives a shorter waterline.
The Kat is lightly loaded most of the time as I only provision when cruising. I have also faired the bottom and keel and replaced the thick rough black bottomkote with VC-17. Overkill I know but she is likely to be the only cruising boat I shall ever own. (Still club race the Thunderbird).
If I am in a rush, which is rarely, I will run at 2500 RPM which gives me 6.5 to 7 knots depending on sea conditions. My GPS/Chart Plotter rarely agrees with my knot meter reading but as I added all new Tack - Tick wireless instruments (before Ray Marine bought them out) I am pretty confident that my speed through water is accurate.
Remind me in the autumn to measure the prop size and pitch.
