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What Size Prop?

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Champipple
Master Marine Consultant

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USA
6855 Posts

Initially Posted - 03/28/2003 : 08:45:53

Anyone who is using a Nissan or Tohatsu 8 hp motor-

What type of prop did you get?

D. Wolff - "The Flying Wasp" #401 sr/sk
Chief Measurer C-25/250 National Assn.
<img src="http://www.flags.com/dreamimages/Flags/measurer.jpg" border=0>

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 03/28/2003 : 09:48:56

Duane, what are your available prop choices for that Nissan ?
(Most small outboards don't have a lot of options available.)

Generally speaking, for a low-speed displacement hull, the prop with the most blades, largest diameter, and lowest pitch is the ticket.

Currently maintaining two holes in the water...'77 Venture 23 and new to the family,
'78 Catalina 25

Edited by - on

Derek Crawford
Master Marine Consultant

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USA
3323 Posts

Response Posted - 03/28/2003 : 10:10:27

Duane - for my Nissan 8 h.p. I had a choice of 3 pitches: 6.5", 7.5" or 8.5". After much discussion with my powerboat friends (yes, I do have 'em!!) I chose the 6.5. It definitely gives more thrust at lower rpm's for when you're manoevring or docking. Running at cruising speed increases the revs by 200 - 300 over the original 7.5" pitch prop (this according to the Nissan factory).
Hope this helps.
Derek

<img src="http://im1.shutterfly.com/procserv/47b3dc30b3127cce942c608d6f1e0000001010" border=0>
TRFK#2262"This Side Up"

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 03/28/2003 : 10:23:05

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
Duane - for my Nissan 8 h.p. I had a choice of 3 pitches: 6.5", 7.5" or 8.5". After much discussion with my powerboat friends (yes, I do have 'em!!) I chose the 6.5. It definitely gives more thrust at lower rpm's for when you're manoevring or docking. Running at cruising speed increases the revs by 200 - 300 over the original 7.5" pitch prop (this according to the Nissan factory).
Hope this helps.
Derek

<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>
it does derek....thank you it is exactly the testimonial I needed.

D. Wolff - "The Flying Wasp" #401 sr/sk
Chief Measurer C-25/250 National Assn.
<img src="http://www.flags.com/dreamimages/Flags/measurer.jpg" border=0>

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 04/11/2003 : 08:14:32

Just Sold the Old Motor on ebay...

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2409681872

and Just bought a new Tohatsu 8hp electric start and alternator, 6.5 pitch prop....

http://www.lebombomarine.com/t8.htm

I am sure I will have alternator questions and battery questions for a lot of you as they surface.

D. Wolff - "The Flying Wasp" #401 sr/sk
Chief Measurer C-25/250 National Assn.
<img src="http://www.flags.com/dreamimages/Flags/measurer.jpg" border=0>

Edited by - on

RichardG
Admiral

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USA
990 Posts

Response Posted - 04/11/2003 : 10:36:19

Duane:

Nice weight. Nice price too.

Good luck!

RichardG 81 C25 SR/FK "Sanity"

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 04/11/2003 : 12:00:57

Nice goin' on the 24 year old Johnson($455.00). That new Tohatsu motor sure is light...Is it Helium filled? <img src=icon_smile_wink.gif border=0 align=middle>

<img src="http://www.catalina25-250.org/c25sm.gif" border=0>Don Lucier<img src="http://www.catalina25-250.org/c25sm.gif" border=0>
<img src="http://im1.shutterfly.com/procserv/47b2d904b3127cce9f7cd9ffdf1d0000003010" border=0>
North Star SR/FK

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 04/11/2003 : 13:17:03

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
Nice goin' on the 24 year old Johnson($455.00). That new Tohatsu motor sure is light...Is it Helium filled? <img src=icon_smile_wink.gif border=0 align=middle>

<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I don't know, but I will tell you I'm a little worried that the lack of the weight will bring the prop out of the water...we only have a couple of inches to play with.

dw

D. Wolff - "The Flying Wasp" #401 sr/sk
Chief Measurer C-25/250 National Assn.
<img src="http://www.flags.com/dreamimages/Flags/measurer.jpg" border=0>

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 04/11/2003 : 19:30:21

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>"...I'm a little worried that the lack of the weight will bring the prop out of the water...we only have a couple of inches to play with."<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I don't think weight is going to have any real effect on whether the motor cavitates or not, because a few pounds doesn't mean much when the 6,000lb, 25ft bronco starts to buck.

If you need a couple of inches, can you lower the bracket on the transom with the extra holes that are provided?

<img src="http://garhauermarine.com/images/product/OB-125.jpg" border=0>

<img src="http://www.catalina25-250.org/c25sm.gif" border=0>Don Lucier<img src="http://www.catalina25-250.org/c25sm.gif" border=0>
<img src="http://im1.shutterfly.com/procserv/47b2d904b3127cce9f7cd9ffdf1d0000003010" border=0>
North Star SR/FK

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 04/11/2003 : 22:28:57

I noticed that Tohatsu offers an extra-long (25") shaft in the 9.8 hp model.. and it's about the same weight. For someone who's venue will inlude some ocean time, that long shaft is pretty attractive... and my back would appreciate the light weight.

Then I see it's a 2 stroke and I can't buy one in California anyway... oh well.

Currently maintaining two holes in the water...'77 Venture 23 and new to the family,
'78 Catalina 25

Edited by - on

RichardG
Admiral

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USA
990 Posts

Response Posted - 04/12/2003 : 12:11:13

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote> I can't buy one in California anyway... oh well<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Just take a short drive to Oregon (plus no sales tax) or Nevada.

RichardG 81 C25 SR/FK "Sanity"

Edited by - on

Champipple
Master Marine Consultant

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USA
6855 Posts

Response Posted - 04/15/2003 : 08:28:20

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>"...I'm a little worried that the lack of the weight will bring the prop out of the water...we only have a couple of inches to play with."<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

I don't think weight is going to have any real effect on whether the motor cavitates or not, because a few pounds doesn't mean much when the 6,000lb, 25ft bronco starts to buck.

If you need a couple of inches, can you lower the bracket on the transom with the extra holes that are provided?

<img src="http://garhauermarine.com/images/product/OB-125.jpg" border=0>

<img src="http://www.catalina25-250.org/c25sm.gif" border=0>Don Lucier<img src="http://www.catalina25-250.org/c25sm.gif" border=0>
<img src="http://im1.shutterfly.com/procserv/47b2d904b3127cce9f7cd9ffdf1d0000003010" border=0>
North Star SR/FK
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

No don trust me - its weight.....

The Cavitation isn't the issue...Motor mount is as low as it will go.

D. Wolff - "The Flying Wasp" #401 sr/sk
Chief Measurer C-25/250 National Assn.
<img src="http://www.flags.com/dreamimages/Flags/measurer.jpg" border=0>

Edited by - Duane Wolff on 04/16/2003 14:05:45

Edited by - on

RichardG
Admiral

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USA
990 Posts

Response Posted - 04/21/2003 : 10:55:40

Duane:

What's the measured shaft length of your new long shaft motor, based on the 'regular' definition of shaft length (cavitation plate to top of motor mounting board)? After hearing that Tohatsu/Nissan specs use a different definition, I measured a motor at Boaters World (they only had standard shaft motors in stock) based on the regular shaft length definition -- I got 17 1/2".

RichardG 81 C25 SR/FK "Sanity"

Edited by - on

Champipple
Master Marine Consultant

Members Avatar

USA
6855 Posts

Response Posted - 04/21/2003 : 14:32:54

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
Duane:

What's the measured shaft length of your new long shaft motor, based on the 'regular' definition of shaft length (cavitation plate to top of motor mounting board)? After hearing that Tohatsu/Nissan specs use a different definition, I measured a motor at Boaters World (they only had standard shaft motors in stock) based on the regular shaft length definition -- I got 17 1/2".

RichardG 81 C25 SR/FK "Sanity"
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Here is the story - about two years ago, we replaced the mounting bracket with a Garelick. Do to the mounting and the travel on the bracket, we had about 1" of water above the skeg. I should note that the bracket isn't going any farther down...we are out of room.For the most part we were fine with that.

Prior to last season, we had no idea that there was about 4 inches of water under the cabin sole...(long story, problem is fixed, water is gone, for additional info look for my posts on mast compression posts) The removal of this water, along with a few other things raised the boat a bit. The old Johnson 9.9 measured 22 inches from skeg to the bottom of the bracket. We corrected this by filling the water tank (which we never did before), moving the anchor aft into the sail locker and moving the back up anchor under the quarterberth. That just about go us our inch back.

The Tohatsu measures 23" for the long shaft (same area) however only weights 75 lbs for the long shaft(I didn't check the exact weight so don't kill me if I am off a few , you'll get the idea in a moment) It also only comes with a 3 gallon tank. So if you look at the weight of 3 less gallons of gas and the 30+ lb difference in the weight of the motor I am hoping I still have a prop in the water...Otherwise its a new mounting bracket

D. Wolff - "The Flying Wasp" #401 sr/sk
Chief Measurer C-25/250 National Assn.
<img src="http://www.flags.com/dreamimages/Flags/measurer.jpg" border=0>

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