First boat... Need help with low rpm/speed

[JimS123]

It has 2 thru transom bolts and 2 clamps for the top. It's not just a clamp on engine.

You have clamps and 2 bolt holes for security. That is what I would refer to as a clamp on motor. It is not adjustable.

A bolt on motor is one with no clamps at all, and a series of 5 vertical bolt holes to enable adjustment. All just semantics.

They key to this dilemma is using the correct prop that will provide the correct wot rpm. When a boat is run near the top end of the max weight requirement, a pitch lower than std would probably be required.

 

[WesNewell]

Installation instructions say to bolt it on and tighten the bolts and clamps. So it has bolts that are required according to manual. that makes it a bolt on engine imo. And if you want to get technical, it's not a motor at all, it's an ICE. And there are many bolt on engines that don't have 5 bolt holes.

 

[WesNewell]

SR, it comes from personal experiences and research. And I've been a boat owner since 1973. Both OB and stern drive. The boat I have now has the smallest engine I've ever owned at 60 hp. And to get the most out of it took a bit of experimenting and researching.

 

[Sea Rider]

In that case all portable motors having 2 through bolts on their brackets should be bolted, as said before it's entirely to each owner if bolting or not bolting their motors to their transoms. I have never bolted any of my personal or my friends motors to their transoms while running at theri max wot rpm range factory stated, none of them has never failed to the deep blue while using the previous posted pic method.

This clamp, bolt on motors talk has deviated from the original tech controversy which is : upper vrs lower plates gap install on tall plates gap lower legs motors which the M40C happens to be such. So if having 4-5-6 notches doesn't apply to this particular type of motor.

WN: where did you get the stated 20% power loss reduction, asume that huge reduction is going on in between plates, right ?

Your 60 Merc install parameters states 250 mm between AV plate and boat's bottom, did you go for such given height when installed the motor on transom ? Would you say that the water flow is crossing at full wot under which plate, the upper or lower one with motor trimed to 90 deg or you don't care at all at which height is passing ?

Has your motor been prop maximized or still running the current prop supposingly the motor was factory delivered with one ?

Happy Boating

 

[WesNewell]

I've told you before.
https://www.thehulltruth.com/boating-forum/820886-prop-selection-advice.html

 

[JimS123]

I agree, we have deviated from the question. Semantic talk is not helping the original poster.

I see that now - if its on hull truth it must be real.

Its funny how old Ole screwed up wayyyy back when, when he called his contraption a rowboat motor. And everyone that subsequently called theirs an outboard motor.

I propose a petition to change every term to "Over-the-transom-internal-combustion-engine", or OTTICE for short.

 

[Sea Rider]

We're dealing with water and boats, not airplanes, cars, trucks, right. So why is that imperative to be called an outboard when in reality it's an "outboard motor" and someone ate the ending and by word of mouth ended being called an outboard. Can call it an OB, outboard,motor, motor, powerplant, so let's not be so picky in the wording each one likes to use...

While we wait for the OP's water trials, findings and answer if still wants to follow his post, why don't we go for an open discussion regarding the eternal conflict AV even the boat's bottom and if someone can answer what requested, if will work OK and why ?

https://forums.iboats.com/forum/gen...p-questions-and-topics/10914282-the-joy-stick

Happy Boating

 

[JimS123]

While we wait for the OP's water trials, findings and answer if still wants to follow his post, why don't we go for an open discussion regarding the eternal conflict AV even the boat's bottom and if someone can answer what requested, if will work OK and why ?

As my Dad used to say: "Let's not do it, but say we did".....LOL

The cavitation plate (haha) topic has been beaten to death. There are different opinions on the subject and nobody is willing to give in. My guess is that the original poster couldn't care less about the argument, but just wants some help for his problem.

 

[Sea Rider]

The issue is that near everybody wants to apply the Jurassic obsolete Merc's height parameters which won't work at all on newer motors.. The only possible way for OP to come with the right answer would be to try both lower leg heights settings that's : flow crossing at wot under the upper and over the lower plate and report which setting worked as a charm in "all water conditions" which is key. If nobody wants to go for the hassle of testing both, just sit their clamp motors even on transom and and beat yourself to the chest that you achieved basic combo propulsion...

The issue isn't that nobody is willing to give in, some wants to give what works well for them and wants all of us to go per same...

Happy Boating

 

[JeffSimons]

I am also in the process of buying my very first boat, which I will use for my fishing trips. It's a small one and it's only a second hand purchase. I have to visit poster's website to check if it's still available and if not, I'll just look for another one.

 

[WesNewell]

SR, To achieve maximum speed, you have to have the least amount of drag. That's what keeping the av plate as high as possible keeping the prop in the water, and the water intake for cooling the engine below the waterline does. This is a simple problem of physics. Something you seem to be unable to grasp. The av plate has been in the same location on every engine made since they were introduced. Another concept you seem unable to grasp. Now if one wants more stability in turns, rough waters, ocean waves, etc., and speed isn't an issue, you can mount the fricking engine as low as you want. So yes, there is more than one engine height fits all, except when it comes to maximum speed in normal calm waters. Then there's only one way to achieve it, and that's maximum prop thrust and the least amount of drag. And that holds true in 1900 as well as now and forever.