question on load when deaing with props

[oxbeast1210]

I was on the tohatsu site seeing what the recomended prop is for my tohatsu m40c and on the side it has a chart that reads:: light load 100-500 medium load 500-1500 and heavy 1500 -3000lb

Im just wondering if the load includes the weight of the hull in other words if my hull weights 1300 lb and the wieght of passangers and all my gear is 600lb totaling 1900 would I have a heavy load or do I not count the weight of the hull putting me at medium load
thank you

 

[steelespike]

Re: question on load when deaing with props

In my opinion the weight includes boat,motor,people and gear. Because that is the weight the motor is pushing.

 

[oxbeast1210]

Re: question on load when deaing with props

1) Performance issue you are trying to correct.
Boat struggles to get on plane unless extra weight on bow
even then it still slow to get up


2) Current prop manufacturer, model, aluminum or stainless as a minimum.

10-2/3 x 11-1/3 RH Michigan Wheel Michigan Match Propeller ,aluminium

3) Current prop diameter and pitch (required).

10-2/3 x 11-1/3
4) Wide open throttle RPM and speed with an average load (very helpful) 5300 with lighter load but loaded for fishing only reaches about 3800...

5) Engine/drive make, model, year, and HP
40 hp tohatsu M40C 1989

6) Boat make model, year, length and weight
sunliner sunmate center console 14 ft weight unknown

You helped me out before on my issue but I didnt get a reponse to my last post was wondeirng if
i could get more advice?

I got the smart tabs as suggested and they do help alot but I would still like to be able to plane loaded for fishing.

should i go down in pitch to 9.9 8.7 or 7.8 ?

if its just me fishing it takes me a about ten seconds but I get on plane and to about 5200 rpm with two people the boat rarely can plane and only gets to about 3800 rpm seems like when it planes the rpm shoot up guessing since there is less ristance from the hull.

 

[pootnic]

Re: question on load when deaing with props

Some pictures may help,your last statement is alittle confusing,to me anyways.
Is your prop coming out the water for the rpms to jump up or maybe you have a spun hub?
Hows the outboard sit on the transom,had this boat long?
Don't know your boat,thinking fiberglass,what year is it,style hull,garage kept?
Could it be real heavy,maybe waterlogged,whats the recommended hp rating?
I guess theres a few more questions I'd like answered before suggesting any other prop...

 

[oxbeast1210]

Re: question on load when deaing with props

Prop is not coming out of the water but after the boat planes the rpms get up if the boat does not plane the rpm stay around 3800 . Hub is not spun. I have done the suggested test. 14 ft fiberglass not garage kept but also not water logged I've had the boat about 3 months now. if its just me the boat takes a little to plane but eventually gets there with two people it wont plane and the rpm stay at about 3800.
according to tohatsu website a m40c with my load is supposed to run a prop that is about 9 in pitch.

 

[jestor68]

Re: question on load when deaing with props

The Tohatso web site is correct.

Get yourself a Solas Amita (aluminum) 12-1/10" X 9". Don't let the low price($84.59) fool you. It will outperform any other aluminum prop on that page.

 

[oxbeast1210]

Re: question on load when deaing with props

The Tohatso web site is correct.

Get yourself a Solas Amita (aluminum) 12-1/10" X 9". Don't let the low price($84.59) fool you. It will outperform any other aluminum prop on that page. [/QUOTE

Sweet I ordered that one you suggested about n.hour ago. Hope it helps

 

[oxbeast1210]

Re: question on load when deaing with props

WIll lowring the pitch drop my top speed down for sure or does it depend on other circumstances?
thank you

 

[jestor68]

Re: question on load when deaing with props

WIll lowring the pitch drop my top speed down for sure or does it depend on other circumstances?
thank you

You will not necessarily lose any top end speed. I have seen many cases where top was increased due the motor turning faster rpm with the reduces pitch, plus the fact that Solas props are simply a better design than some others; especially in the aluminum category.

 

[oxbeast1210]

Re: question on load when deaing with props

COol i will update with results

 

[oxbeast1210]

Re: question on load when deaing with props

Well I got the prop today but the diameter does not work with my motor it causes the prop to hit the cavitation plate .. the only prop they carry that looks like it might work is the

Solas 4 blade 9 pitch but i'm worried that the pitch wont be low enough for a 4 blade what do you all think?

 

[steelespike]

Re: question on load when deaing with props

It appears the M40C is a 2 cylinder 1.92 ratio and uses props with a slightly lower diameter from the M40D a 3 cylinder with a 1.85 ratio.
Tohatsu props a 10.8 X 9.9 361B641090 and a 11.2 X 8.7 is 348W641070.

 

[steelespike]

Re: question on load when deaing with props

It appears the M40C is a 2 cylinder 1.92 ratio and uses props with a slightly lower diameter from the M40D a 3 cylinder with a 1.85 ratio.
Tohatsu props a 10.8 X 9.9 361B641090 and a 11.2 X 8.7 is 348W641070.
largest diameter M40C is 11.6 M40D is 12.1.
It appears the Solas props are for the M40D
4 blade for the M40C is 11.4 X 7.1 348W641080.Mopre than you need.
I think you should stick with props in this ball park.
I believe the M40C is rated for 5200 to 5800.
I'm thinking an 8.7 is a good size.If its too light you can still use it by watching the rpm.
Should get your load up easily If it makes 5800 speed is a little over 22.
You could try the 9.9. It will be slower getting the load up but could make a little more speed
if it can wind up surely go pretty good lightly loaded.

 

[oxbeast1210]

Re: question on load when deaing with props

Thank you steel,
do you or anyone on this forum sell these props ? I would like to support someone from the forum.
Thanks

 

[steelespike]

Re: question on load when deaing with props

I don't think anyone sells these prop here. Someone may have a take off though I would be inclined to go with new.
I got the info from a Tohatsu site. I just used google and put in Tohatsu props.