tinkicker0
Well-Known Member
Has anyone ever encountered the signs of an overpropped engine when slipping the boat in still conditions freshwater, ie will not pull the published RPMs with the OEM recommended prop, which was probably manufacturer tested in saltwater.
My thinking is that freshwater being less dense will allow the boat to sit deeper in the water and hence produce more total drag.
My mercruiser 3.0l will only pull 3800 rpm / 29 GPS mph at wide open throttle with the OEM recommended 21" prop when the owners handbook book says 4500 rpm / 40 mph max speed.
The engine redlines at 5000 rpm / 33mph with a 19P prop.
All compressions are within the 180 -190 psi band (hot).
New plugs, leads, distributor cap, rotor arm and timing checked as spot on. Throttle plates do open fully at WOT, choke flaps disconnected and locked in open position, so not closing off choke chimney.
Flame arrestor is clean. Engine runs sweetly otherwise and is always a first time starter.
Gearing in sterndrive is correct for engine model and OEM.
2 persons on board plus a cuddy full of typical overnighting gear, bedding, stoves, beer supplies etc.
Underside is antifouled, no major dings and she has only been back in the water for two months oh and the prop is new this season, never been dinged. No signs of the ubiquitous plastic bag stuck to it either.
So it is either:
1. Boat cannot physically achieve 40 mph in still freshwater as loaded.
2. Boat when originally tested by Bayliner was very shy of fuel, had lester piggott alone at the helm, had a following wind and ideal chop in a salty sea.
3. Bayliner "exagerrated" their performance claims for the 1952 cuddy in the published handbook.
Any one any ideas, real life Bayliner 1952 freshwater GPS performance figures or opinions?
Hate it when apparently down on performance, she gets up on plane very smartly, then bogs down at 29 mph / 3800 rpm like being overpropped.
My thinking is that freshwater being less dense will allow the boat to sit deeper in the water and hence produce more total drag.
My mercruiser 3.0l will only pull 3800 rpm / 29 GPS mph at wide open throttle with the OEM recommended 21" prop when the owners handbook book says 4500 rpm / 40 mph max speed.
The engine redlines at 5000 rpm / 33mph with a 19P prop.
All compressions are within the 180 -190 psi band (hot).
New plugs, leads, distributor cap, rotor arm and timing checked as spot on. Throttle plates do open fully at WOT, choke flaps disconnected and locked in open position, so not closing off choke chimney.
Flame arrestor is clean. Engine runs sweetly otherwise and is always a first time starter.
Gearing in sterndrive is correct for engine model and OEM.
2 persons on board plus a cuddy full of typical overnighting gear, bedding, stoves, beer supplies etc.
Underside is antifouled, no major dings and she has only been back in the water for two months oh and the prop is new this season, never been dinged. No signs of the ubiquitous plastic bag stuck to it either.
So it is either:
1. Boat cannot physically achieve 40 mph in still freshwater as loaded.
2. Boat when originally tested by Bayliner was very shy of fuel, had lester piggott alone at the helm, had a following wind and ideal chop in a salty sea.
3. Bayliner "exagerrated" their performance claims for the 1952 cuddy in the published handbook.
Any one any ideas, real life Bayliner 1952 freshwater GPS performance figures or opinions?
Hate it when apparently down on performance, she gets up on plane very smartly, then bogs down at 29 mph / 3800 rpm like being overpropped.
