All, wondering if there is a pitch of choice on my2004 lund 1700 fisherman and a yamaha f115...pickin up a new OB and am wondering what to pitch it with....thx guys.
The Sylvan 1700 Expedition Sport is the nearest and was tested with a 21" Aluminum, and that is right in the ballpark. It turns at 5800RPM doing 45.6mph. With more weight(kicker, maybe 3 adults) and pushing the bimini, I'd say you are closer to a 19", especially if it is Stainless Steel.
My 18Ft Fiberglass with an F115 weighs about 500lbs more and has a 17", and will even turn a 19" at less than 6000.
I run 17s on my 5000 lb boat with twin 80s. With a light load, I watch my high throttle range as the engines will reach the rev-limiter if I go to the stop and we know that is not good.
It seems like most of the failures I've seen have been main bearings/cranks that fail due to loading with a steeper pitched prop. I've only seen one failure on these mid range four strokes that were able to turn 6000 RPM....... that motor was constantly run against the rev limiter for a couple of weeks and wound up snapping the connecting rod and sent it through the crank case. So, if you're in that range you should avoid giving more throttle than about 5900 RPM. It's a fine line. I believe that the rev limiter is around 6150 RPM.
Out of curiosity, what RPM was your F80 able reach at WOT with a normal load in the boat and the prop you were running?
Thanks for all the replies guys...My F80 would Tap out WOT at 5500-5700.. not sure the prop pitch, factory white when I bought it, worked it hard and when I run the salt I run WOT if the water is good enough for 1.5 hrs or so very often haulin 3 guys kicker gear a few crab pots etc......always purred..worked hard for 8 years but was alway maintained well...ohh well, the F80 got sold to a guy in Arlington apparently he was able to overlay and machine the crank...buy new bearings, main and rod caps, flush all passages and It is running. I am excited for the 115 and appreciate all the info guys...
