# Prop suggestion Chittum LM2 50 tohatsu



## Salt (Mar 19, 2019)

Some report 39 mph with Powertech SCB3 15p.


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## Xcapnjoe (Jun 5, 2013)

Salt said:


> Some report 39 mph with Powertech SCB3 15p.


That's almost exactly what I get with mine! HB Waterman. 50 HP Tohatsu tiller.
I lose about 10 MPH when the motor is fully jacked up.

I'm trying a 4 blade PT next week. 10.75 13P I think. It's the cupped prop.
Waiting on delivery...


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## CKEAT (Aug 26, 2015)

A foreman prop is for very shallow water performance as the LMII is. IMO if speed is the goal that’s not just the wrong prop, it’s the wrong boat. 

That’s just an opinion, relax folks. 

I would go ahead and go with the 12degree mangrove if performance is the goal.


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## Rich11111 (Jun 6, 2018)

CKEAT said:


> A foreman prop is for very shallow water performance as the LMII is. IMO if speed is the goal that’s not just the wrong prop, it’s the wrong boat.
> 
> That’s just an opinion, relax folks.
> 
> I would go ahead and go with the 12degree mangrove if performance is the goal.


I think the poster is looking for prop suggestions not weather he needs a new boat or did I miss read the question?


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## Sublime (Oct 9, 2015)

Rich11111 said:


> I think the poster is looking for prop suggestions not weather he needs a new boat or did I miss read the question?


Yes, it's like buying an F350 and saying you want it to corner like a Porsche.


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## coconutgroves (Sep 23, 2013)

Xcapnjoe said:


> That's almost exactly what I get with mine! HB Waterman. 50 HP Tohatsu tiller.
> I lose about 10 MPH when the motor is fully jacked up.
> 
> I'm trying a 4 blade PT next week. 10.75 13P I think. It's the cupped prop.
> Waiting on delivery...


How is your hole shot in the skinny?


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## Xcapnjoe (Jun 5, 2013)

coconutgroves said:


> How is your hole shot in the skinny?


Suits me. The aluminum 4 blade 12P 10.75 diameter prop that George gave me when I bought it jumped up scary fast, but it hit the rev limiter in no time. The three is not as snappy but it throws it up in a boat length or so.

Hoping the cupping and the added pitch will work on the new prop.
I tried a 4blade 14P 11.25 diameter and it was a dog. Took three boat lengths.

Props are weird.


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## Smackdaddy53 (Dec 31, 2012)

Rich11111 said:


> I think the poster is looking for prop suggestions not weather he needs a new boat or did I miss read the question?


Why are you replying here? I don’t see you recommending a prop so pipe down and let people have a discussion.


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## Rich11111 (Jun 6, 2018)

I replied because I am interested in true responses to original question as I have a similar boat and curios as to options. I have a Foreman prop and want to know backup possibilities


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## Smackdaddy53 (Dec 31, 2012)

Rich11111 said:


> I replied because I am interested in true responses to original question as I have a similar boat and curios as to options. I have a Foreman prop and want to know backup possibilities


CKEAT has one coming very soon and he was making a statement which is part of a discussion forum.


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## coconutgroves (Sep 23, 2013)

Xcapnjoe said:


> Suits me. The aluminum 4 blade 12P 10.75 diameter prop that George gave me when I bought it jumped up scary fast, but it hit the rev limiter in no time. The three is not as snappy but it throws it up in a boat length or so.
> 
> Hoping the cupping and the added pitch will work on the new prop.
> I tried a 4blade 14P 11.25 diameter and it was a dog. Took three boat lengths.
> ...


I just got a Whipray with a Tohatsu 50 4 stroke on it. The first owner has a 9.5" Powertech on it, 3 blade 13 pitch. It tops out at 35mph with a light load. No jack or compression plate yet.

But, I measured the lower unit and there is 12" of clearance on that shaft. I really wondered why such a small prop was used on a 50 hp engine with good torque. But it seems like running a larger prop on this could have diminishing value.

That 4 blade will get you up faster, but it won't get you the same top end, especially if you are adding cup to it. I would not expect a similar speed number you have with the 3 blade. 39 top end on a Waterman is smoking.

One item to call out on the Tohatsu engine is the load on the lower unit. While I don't have first hand info on this directly from someone who had this happen, I have heard of sheared lower unit drive shafts due to overloading. What I don't know is why and what caused this. Too heavy a prop? Compression plate? Kevin at Fibertek / Stiffy mentioned this to me when I talked to him recently - he steered me towards a small plate for this engine instead of a larger one due to lower unit load concerns. It may be a combination of things and how the boat is run, not an issue or defect with the engine itself. Maybe others have something to share on this.

I have not talked to Jack yet about this rig and his thoughts. I may just go with a PT SCB 3 blade to begin with, run it for a bit, then take next steps. I do know that I need a jack and compression plate (some call it cavitation plate), I am just not clear yet on needing a 14p or 15p prop. I will go 3 blade however - I run a 15p 3 blade Foreman on my B2 and the hole shot was great, but topped out at 31 / 32 mph in good conditions.


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## Smackdaddy53 (Dec 31, 2012)

coconut, the Tohatsus have a weak prop shaft, that could be one of the reasons they didn’t offer a larger prop from the factory.


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## CKEAT (Aug 26, 2015)

Rich11111 said:


> I think the poster is looking for prop suggestions not weather he needs a new boat or did I miss read the question?


It is simply a statement because if one is looking for those traits in that boat they may be disappointed. 

I sure wouldn’t dream of an LMII for any other reason that serous shallow water performance. A huge part of that is getting out of where you got in. 

Oh, also. Did you offer a prop for that rig? Did I miss it?


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## coconutgroves (Sep 23, 2013)

Smackdaddy53 said:


> coconut, the Tohatsus have a weak prop shaft, that could be one of the reasons they didn’t offer a larger prop from the factory.


Good to know, so that does confirm the load issue I mentioned.


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## coconutgroves (Sep 23, 2013)

@obrientimm - check out this post from @Israel luis :









T60 v F70


Goods / Bads / Others? Really happy with my F70, but seems like the new Tohatsu MFS60 weighing in at just 213 lbs is the new hotness. Anyone have any info on: issues reliability durability noise/vibrations power to weight self maintenance ease Also, unrelated, but what’s the deal with the...




www.microskiff.com





Lots of good stats in there


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## Smackdaddy53 (Dec 31, 2012)

coconutgroves said:


> Good to know, so that does confirm the load issue I mentioned.


A few guys with the Tohatsu 50 put a heavy cupped Foreman on it and the prop shaft sheared off, one did it with the stock prop I believe.


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## POCtied (Oct 19, 2016)

Smackdaddy53 said:


> A few guys with the Tohatsu 50 put a heavy cupped Foreman on it and the prop shaft sheared off, one did it with the stock prop I believe.


good thing I got the 60 then. 

I'm seeing 35mph with two and a full load with a Foreman on the 60 18' waterman. Not the same hull, but should be heavier and more drag than the LM2


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## Dben (Sep 20, 2020)

Harry Spear recommended a SCB3 16p for a T60 on an EvergladeZ he's building for me. I'd guess that the first response to your post is probably a pretty good starting place.


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## Rookiemistake (Jan 30, 2013)

Does the 50 and 60 share the same prop shaft?interested since i was thinking of repowering


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## Xcapnjoe (Jun 5, 2013)

coconutgroves said:


> I just got a Whipray with a Tohatsu 50 4 stroke on it. The first owner has a 9.5" Powertech on it, 3 blade 13 pitch. It tops out at 35mph with a light load. No jack or compression plate yet.
> 
> But, I measured the lower unit and there is 12" of clearance on that shaft. I really wondered why such a small prop was used on a 50 hp engine with good torque. But it seems like running a larger prop on this could have diminishing value.
> 
> ...


I wondered the same thing about the prop size George put on the motor until he said it was "free." The 60 HP Merc I replaced had a much larger prop.
He said it was just for puttering around until I got the 3 blade, which I ordered from Jeff at Olympic before the motor arrived.

Avery at Hell's Bay said to try the 10.75 4 blade with a little cupping. Jeff suggested the SCW in a 13P. I was incorrect earlier when I said 14.

I'll figure it out eventually.

Interesting what Smack said about the prop shaft shearing off under heavy load. Makes me feel a little bit better about the SCW413P.
Hopefully it's on the money and will negate any weaknesses.


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## coconutgroves (Sep 23, 2013)

Avery knows his stuff, please do post results.


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## Pudldux (Mar 3, 2016)

I’m sure jack can build or recommend a prop for top end over hole shot.


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## obrientimm (Jan 28, 2013)

Foreman prop that came with my Chittum performs fine. Great hole shot and grip in turns. I can not get over 5300 rpm even my trimming or lifting jp. I found a PT scb 15p without cup. Jumped up fine but hit the rev limiter at 1/2-3/4 throttle. Not sure if I can add enough cup to compensate


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## Smackdaddy53 (Dec 31, 2012)

obrientimm said:


> Foreman prop that came with my Chittum performs fine. Great hole shot and grip in turns. I can not get over 5300 rpm even my trimming or lifting jp. I found a PT scb 15p without cup. Jumped up fine but hit the rev limiter at 1/2-3/4 throttle. Not sure if I can add enough cup to compensate


Why add cup to a shelf prop instead of having Jack tweak his prop? Give him a call, I bet he could just bend the blades back a little and allow you to get your RPM and possibly take some cup out of it but you are going to lose some of your hole shot and cornering grip. 
Are you not seeing speeds you want? 33-34mph is about tops with that hull and outboard unless you get a speed prop which will pretty much defeat the purpose of having a tunnel.


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## Redhead (Apr 18, 2018)

I’m running a Baumann bullet 3S 12 1/8 15 pitch with heavy cup on my LM1 tunnel. I see 33-35 at 5800 rpms. It jumps up and grips great.


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## sjrobin (Jul 13, 2015)

I have not seen more than 31 mph on a LM tunnel, but not sure why more speed is good
Three different skiffs, two with 50hp one with 60hp. The non tunnel will do 34/35


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## Capt.Ron (Mar 5, 2014)

coconutgroves said:


> I just got a Whipray with a Tohatsu 50 4 stroke on it. The first owner has a 9.5" Powertech on it, 3 blade 13 pitch. It tops out at 35mph with a light load. No jack or compression plate yet.
> 
> But, I measured the lower unit and there is 12" of clearance on that shaft. I really wondered why such a small prop was used on a 50 hp engine with good torque. But it seems like running a larger prop on this could have diminishing value.
> 
> ...


Ask Dini, he has a MFS60 on his...... it’s a skim board


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## coconutgroves (Sep 23, 2013)

Capt.Ron said:


> Ask Dini, he has a MFS60 on his...... it’s a skim board


Will do, thanks man


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