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Author Topic:   13-footer: Propeller

Bjornas posted 11-21-2006 10:01 PM ET (US)
After reading everyone's post about props it got me thinking I haven't even considered what prop I should run on my classic 13 Whaler. The motor came with 12.5 Aluminum prop in very good condition. The manual states the boat should run between 5,000 - 5,700 at WOT.
Any suggestions? I have read some posts about most 13's using a 13 inch prop.
I am looking for good planing with decent top end speed and no porposing.
Any suggestions are appreciated so I can be ready to go next spring. Are there options for the Tohatsu motors?
Thanks in advance.
1972 13 Whaler
40 Tohatsu short shaft - Power Trim and Tilt
http://i114.photobucket.com/albums/n270/bjornas/Lower_Unit.jpg
-R
Bjornas posted 11-23-2006 12:12 AM ET (US)
Ok,
So it's not an E-TEC or a Merc. It still deserves a decent prop right? Where are all the gods of performance when I need them?
Tom W Clark posted 11-23-2006 12:18 AM ET (US)
I have no idea what kind of propeller is used on Tohatsu outboard motors, but maybe with some more information, we could figure it out together.
Why not start with the usual required information? We have the WOT range. Good. What about the gear ratio? How about a performance report of what you have on it now? How about a list of what props Tohatsu offers?
Bjornas posted 11-23-2006 01:24 AM ET (US)
Tom!
Unfortunately I just purchased the engine, and the boat is in the middle of being restored so I have never run this combination. The first time it will see the water is next spring when it is completed. (Bought the hull and motor separate) So yes, this will be somewhat of a guess, which is why I need the sage advice of the performance gods.
The gear reduction ratio as stated in the owners manual is 13:24
The list of props from the Tohatsu web site I don't think apply to my engine as it is a carbed 40 hp two stroke. I believe the list is just for the newer TLDI motors.
http://www.tohatsu.com/tech_info/prop.html
I went to propline.com and looked up Michigan "Rapture" for my engine and the following selection came up.
http://www.propline.com/Select-Boat-Props-By-Brand/Michigan-Wheel/ Rapture-Performance-Stainless-Steel-Michigan-Wheel/ Nissan_Tohatsu_Outboards/35_50.htm
The only stamps on the current stock aluminum prop is a 12.5 stamped on it along with a "C" stamp.
The prop chart in the manual does not give pitch and diameter. Only a column labled "Mark". It indicates for my motor C 12.5 which is exactly what is stamped on the current prop. I am assuming the 12.5 is diameter. There is no other indication for pitch that I can determine.
Is there anything else I should look up?
Tom W Clark posted 11-23-2006 01:41 AM ET (US)
Let's use jimh's Propeller Calculator and see what happens.
5500 RPM with a 1.84 gear ratio (24/13) and 10 percent slip at 35 MPH (what your boat will probably do) suggests a 13-14 inch-ish pitch prop.
"12.5" probably refers to pitch, but who knows? It's probably close though to what you need but maybe a little short.
Next spring when you have i all together, go run the prop you have now and see how it does. Report back to us and maybe we can fine tune your prop selection and improve the performance.
Most 13 footers with 35-40 HP use 13" pitch props.
Bjornas posted 11-23-2006 01:53 AM ET (US)
I just figured out what the "C" means. It refers to load weight.
HL = Heavy load
C = Cruise
LL = Light Load

The bar graph next to it shows numbers getting larger as the load is lighter, so I assume the 12.5 = pitch?
Either way, you don't think I should make an educated guess and get a prop ahead of time?
I was thinking a nice Stainless prop. Do you recommend just staying with an aluminum for a 13?
Tom W Clark posted 11-23-2006 11:52 AM ET (US)
You should really run the boat with the pro you have so you can establish a baseline of data. That is the only good way top make an informed decision on a new propeller.
A stainless steel prop is not going to make a huge difference in performance on a 13 but if certainly is going to be more durable. I think you should consider one. I can get you a Stiletto or Turbo for less than those Michagans noted above.
Binkie posted 11-23-2006 12:50 PM ET (US)
Go. to Ron hill, a prop builder in Ca. He builds the props for a class of raceboat called California C. It is a tunneled hull boat that uses Tohatso 40 motors with standard fishing lower units exclusively. He probably can help you out with your prop selection. He has a vast knowledge of outboard props.
Rich
Bjornas posted 11-23-2006 09:34 PM ET (US)
Tom,
That sounds great, will I need a hub kit for that kind of prop? Preferably I would like a prop that just fits on but let me know what size you suggest. I don't know the difference between the Stilleto and the turbo. Any comments you could add would be great.
Binkie,
Thanks for the feedback, I went to hillmarine.com and sent them an email about my rig and requested recommended pitch and diameter prop for my boat. It will be interesting to hear what they say.
Boatplans posted 11-23-2006 11:37 PM ET (US)
Propeller rebuild shops with walls full of used propellers will normally allow a cash paying customer to do tryouts. A Boston Whaler 13 footer with a Tohatsu 40 should perform well with a variety of propellers. I would not waste much time choosing a propeller for your bullet proof boat and motor. Experiment first with trim before going to the propeller shop.
Bjornas posted 11-26-2006 12:49 AM ET (US)
Hi Boatplans,
Unfortunately I don't know of a prop shop around here in MA that has that kind of arrangement. My thinking is there are only two or three sizes of prop for my particular setup. If I go with a 13 pitch it may turn out that I could be operating a little above my recommended WOT range with a light load. At least that prop would be good for heavy loads, and or pulling kneeboarders if the occasion arose. If I go with a 14 pitch it may only perform well with light loads but give me excellent top end performance. Whatever choice is made I bet it will give me better performance than the aluminum 12.5 pitch prop on there now that I bet will max out RPM way to early. Not to mention it is Christmas time and my family has been asking what I want.

Tom,
Stilleto or Turbo? Where do I sign up?
Tom W Clark posted 11-26-2006 01:51 PM ET (US)
A Stiletto or Turbo will slide right on your motor with the parts supplied.
Next spring, after you have run her with the prop you have and gotten some baseline data, I will be happy to sell you to appropriate propeller.
Bjornas posted 11-27-2006 10:49 PM ET (US)
Tom,
Your skirting the question. If you had to make a best guess at what prop would give the best all around performance for my rig, what would it be? what make? and why?
Let's live in the hypothetical for a moment.
-R
Tom W Clark posted 11-27-2006 10:57 PM ET (US)
10-1/2" x 13" Turbo Hot Shot.
Bjornas posted 11-28-2006 01:02 AM ET (US)
Thanks Tom,
Can you send me an email with the price and shipping specifics?
-R
Martman posted 11-28-2006 10:29 AM ET (US)
Bjornas,
I've had several 40-50hp tohatsu motors on 13' whalers. I seem to recall using a 15 pitch stainless that I ordered from Cabela. This prop worked well for me even loaded down. When running alone, trimed out, they would fly.
Marty
Bjornas posted 11-29-2006 08:49 PM ET (US)
Hi Martman,
I could see the 50 possibly turning the 15 to WOT range, but the 40?
Is there any way for you to verify?
Thanks

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Author	Topic: 13-footer: Propeller
Bjornas	posted 11-21-2006 10:01 PM ET (US) After reading everyone's post about props it got me thinking I haven't even considered what prop I should run on my classic 13 Whaler. The motor came with 12.5 Aluminum prop in very good condition. The manual states the boat should run between 5,000 - 5,700 at WOT. Any suggestions? I have read some posts about most 13's using a 13 inch prop. I am looking for good planing with decent top end speed and no porposing. Any suggestions are appreciated so I can be ready to go next spring. Are there options for the Tohatsu motors? Thanks in advance. 1972 13 Whaler 40 Tohatsu short shaft - Power Trim and Tilt http://i114.photobucket.com/albums/n270/bjornas/Lower_Unit.jpg -R
Bjornas	posted 11-23-2006 12:12 AM ET (US) Ok, So it's not an E-TEC or a Merc. It still deserves a decent prop right? Where are all the gods of performance when I need them?
Tom W Clark	posted 11-23-2006 12:18 AM ET (US) I have no idea what kind of propeller is used on Tohatsu outboard motors, but maybe with some more information, we could figure it out together. Why not start with the usual required information? We have the WOT range. Good. What about the gear ratio? How about a performance report of what you have on it now? How about a list of what props Tohatsu offers?
Bjornas	posted 11-23-2006 01:24 AM ET (US) Tom! Unfortunately I just purchased the engine, and the boat is in the middle of being restored so I have never run this combination. The first time it will see the water is next spring when it is completed. (Bought the hull and motor separate) So yes, this will be somewhat of a guess, which is why I need the sage advice of the performance gods. The gear reduction ratio as stated in the owners manual is 13:24 The list of props from the Tohatsu web site I don't think apply to my engine as it is a carbed 40 hp two stroke. I believe the list is just for the newer TLDI motors. http://www.tohatsu.com/tech_info/prop.html I went to propline.com and looked up Michigan "Rapture" for my engine and the following selection came up. http://www.propline.com/Select-Boat-Props-By-Brand/Michigan-Wheel/ Rapture-Performance-Stainless-Steel-Michigan-Wheel/ Nissan_Tohatsu_Outboards/35_50.htm The only stamps on the current stock aluminum prop is a 12.5 stamped on it along with a "C" stamp. The prop chart in the manual does not give pitch and diameter. Only a column labled "Mark". It indicates for my motor C 12.5 which is exactly what is stamped on the current prop. I am assuming the 12.5 is diameter. There is no other indication for pitch that I can determine. Is there anything else I should look up?
Tom W Clark	posted 11-23-2006 01:41 AM ET (US) Let's use jimh's Propeller Calculator and see what happens. 5500 RPM with a 1.84 gear ratio (24/13) and 10 percent slip at 35 MPH (what your boat will probably do) suggests a 13-14 inch-ish pitch prop. "12.5" probably refers to pitch, but who knows? It's probably close though to what you need but maybe a little short. Next spring when you have i all together, go run the prop you have now and see how it does. Report back to us and maybe we can fine tune your prop selection and improve the performance. Most 13 footers with 35-40 HP use 13" pitch props.
Bjornas	posted 11-23-2006 01:53 AM ET (US) I just figured out what the "C" means. It refers to load weight. HL = Heavy load C = Cruise LL = Light Load The bar graph next to it shows numbers getting larger as the load is lighter, so I assume the 12.5 = pitch? Either way, you don't think I should make an educated guess and get a prop ahead of time? I was thinking a nice Stainless prop. Do you recommend just staying with an aluminum for a 13?
Tom W Clark	posted 11-23-2006 11:52 AM ET (US) You should really run the boat with the pro you have so you can establish a baseline of data. That is the only good way top make an informed decision on a new propeller. A stainless steel prop is not going to make a huge difference in performance on a 13 but if certainly is going to be more durable. I think you should consider one. I can get you a Stiletto or Turbo for less than those Michagans noted above.
Binkie	posted 11-23-2006 12:50 PM ET (US) Go. to Ron hill, a prop builder in Ca. He builds the props for a class of raceboat called California C. It is a tunneled hull boat that uses Tohatso 40 motors with standard fishing lower units exclusively. He probably can help you out with your prop selection. He has a vast knowledge of outboard props. Rich
Bjornas	posted 11-23-2006 09:34 PM ET (US) Tom, That sounds great, will I need a hub kit for that kind of prop? Preferably I would like a prop that just fits on but let me know what size you suggest. I don't know the difference between the Stilleto and the turbo. Any comments you could add would be great. Binkie, Thanks for the feedback, I went to hillmarine.com and sent them an email about my rig and requested recommended pitch and diameter prop for my boat. It will be interesting to hear what they say.
Boatplans	posted 11-23-2006 11:37 PM ET (US) Propeller rebuild shops with walls full of used propellers will normally allow a cash paying customer to do tryouts. A Boston Whaler 13 footer with a Tohatsu 40 should perform well with a variety of propellers. I would not waste much time choosing a propeller for your bullet proof boat and motor. Experiment first with trim before going to the propeller shop.
Bjornas	posted 11-26-2006 12:49 AM ET (US) Hi Boatplans, Unfortunately I don't know of a prop shop around here in MA that has that kind of arrangement. My thinking is there are only two or three sizes of prop for my particular setup. If I go with a 13 pitch it may turn out that I could be operating a little above my recommended WOT range with a light load. At least that prop would be good for heavy loads, and or pulling kneeboarders if the occasion arose. If I go with a 14 pitch it may only perform well with light loads but give me excellent top end performance. Whatever choice is made I bet it will give me better performance than the aluminum 12.5 pitch prop on there now that I bet will max out RPM way to early. Not to mention it is Christmas time and my family has been asking what I want. Tom, Stilleto or Turbo? Where do I sign up?
Tom W Clark	posted 11-26-2006 01:51 PM ET (US) A Stiletto or Turbo will slide right on your motor with the parts supplied. Next spring, after you have run her with the prop you have and gotten some baseline data, I will be happy to sell you to appropriate propeller.
Bjornas	posted 11-27-2006 10:49 PM ET (US) Tom, Your skirting the question. If you had to make a best guess at what prop would give the best all around performance for my rig, what would it be? what make? and why? Let's live in the hypothetical for a moment. -R
Tom W Clark	posted 11-27-2006 10:57 PM ET (US) 10-1/2" x 13" Turbo Hot Shot.
Bjornas	posted 11-28-2006 01:02 AM ET (US) Thanks Tom, Can you send me an email with the price and shipping specifics? -R
Martman	posted 11-28-2006 10:29 AM ET (US) Bjornas, I've had several 40-50hp tohatsu motors on 13' whalers. I seem to recall using a 15 pitch stainless that I ordered from Cabela. This prop worked well for me even loaded down. When running alone, trimed out, they would fly. Marty
Bjornas	posted 11-29-2006 08:49 PM ET (US) Hi Martman, I could see the 50 possibly turning the 15 to WOT range, but the 40? Is there any way for you to verify? Thanks