Philster
Captain
- Joined
- Sep 15, 2009
- Messages
- 3,344
Re: Wax the bottom?
Well, he'll be waxin' his toboggan if he's smart.
Anyway... lugging happens whenever you stress the internals of an engine under a load that prevents it from running up to its max operating RPM range. So, if you have an engine whose max RPM range is 4600-4800 and you have a prop on it that is just too big and the engine runs the boat/load up to 4000 while you lean on it, and she offers nothing more, and then run all over and go around pulling tubers and generally just using your boat as usual, you are at an increased risk of internal engine damage: E.g, valve-train damage or extra wear on bearings, etc. This is not mysterious or disputed as far as I know. We have an entire prop section here littered with advice on how to ensure you are propped correctly, with one danger of being over-propped being internal engine stress/wear/damage.
While we've drifted from a little growth to issues over serious growth, there are also numerous posts wherein one member suggests to the other member that their under-performing engine/boat might be significantly hindered by growth. If the growth is so significant that it actually puts additional load on an engine, akin to the over-propped issue, then the engine will be lugged and fail to reach its maximum RPM range.
If you have two identical boats, Sasto, that both weigh 2500 lbs, you can safely run a 300 HP engine or even a 115 engine (for sake of an example), and you can do both safely without lugging the smaller engine, because the smaller engine will -- when set up properly -- have different gearing, and the final (bot not lone) say in what that gearing is will be the prop size/pitch. The bigger one will turn a much bigger prop -- maybe a 25p or more -- and the li'l 115 might be turning something several sizes down in pitch. As long as this 'gear reduction' allows each engine to reach its max operating range, all is good. The l'il 115 will whir away and maybe hit 30 MPH all while not lugging, and the Big 300 might be hitting 70+, but the load on each engine is the same. That is the wonder of gear reduction.
Now, since it has been long established that lugging an engine is bad (apologies to Mercury and every other engine maker ever for referencing their established reality) we should avoid lugging the engine: overpropping, over-loading via excessive weight, drag, etc.
It doesn't matter if the lugging is caused by trying to pull 30 Bozo the Clown imitators on broken toboggans or is caused by half the world's barnacles clinging to the bottom of the hull. If the engine is overloaded (lugged) in such a way that it is preventing from reaching its max RPM range, engine wear/damage is risked.
Well, he'll be waxin' his toboggan if he's smart.
Anyway... lugging happens whenever you stress the internals of an engine under a load that prevents it from running up to its max operating RPM range. So, if you have an engine whose max RPM range is 4600-4800 and you have a prop on it that is just too big and the engine runs the boat/load up to 4000 while you lean on it, and she offers nothing more, and then run all over and go around pulling tubers and generally just using your boat as usual, you are at an increased risk of internal engine damage: E.g, valve-train damage or extra wear on bearings, etc. This is not mysterious or disputed as far as I know. We have an entire prop section here littered with advice on how to ensure you are propped correctly, with one danger of being over-propped being internal engine stress/wear/damage.
While we've drifted from a little growth to issues over serious growth, there are also numerous posts wherein one member suggests to the other member that their under-performing engine/boat might be significantly hindered by growth. If the growth is so significant that it actually puts additional load on an engine, akin to the over-propped issue, then the engine will be lugged and fail to reach its maximum RPM range.
If you have two identical boats, Sasto, that both weigh 2500 lbs, you can safely run a 300 HP engine or even a 115 engine (for sake of an example), and you can do both safely without lugging the smaller engine, because the smaller engine will -- when set up properly -- have different gearing, and the final (bot not lone) say in what that gearing is will be the prop size/pitch. The bigger one will turn a much bigger prop -- maybe a 25p or more -- and the li'l 115 might be turning something several sizes down in pitch. As long as this 'gear reduction' allows each engine to reach its max operating range, all is good. The l'il 115 will whir away and maybe hit 30 MPH all while not lugging, and the Big 300 might be hitting 70+, but the load on each engine is the same. That is the wonder of gear reduction.
Now, since it has been long established that lugging an engine is bad (apologies to Mercury and every other engine maker ever for referencing their established reality) we should avoid lugging the engine: overpropping, over-loading via excessive weight, drag, etc.
It doesn't matter if the lugging is caused by trying to pull 30 Bozo the Clown imitators on broken toboggans or is caused by half the world's barnacles clinging to the bottom of the hull. If the engine is overloaded (lugged) in such a way that it is preventing from reaching its max RPM range, engine wear/damage is risked.
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