What Size Outboard

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What Size Outboard

Postby Brent65 on Tue Nov 30, 2021 8:43 pm

Pocketship Dudes and Dudettes,

Having decided to go with a traditional gas outboard, my next question is 2.5hp or 3.5hp? The Tohatsu 3.5 weights about 10 lbs more than the Suzuki 2.5. Do I need the extra power of the 3.5? Is it worth 10 extra pounds on the transom of PS? Will it make PS stern heavy? Do please contribute your thoughts which are always much appreciated.

Best,
Brent
Brent Butikofer
Build Blog: http://www.idahopocketship.wordpress.com
Previous Builds: Scamp, Skiff America 20
Never Stop Exploring
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Re: What Size Outboard

Postby afairaizl on Tue Nov 30, 2021 8:55 pm

Brent,

When I talked with John at the Woodenboat Show in Mystic this year I discussed the tides where I'm at in NH - we have 9ft tidal ranges and the tidal current around Portsmouth Harbor is about 4 kts. With that info it was suggested I go for 4 hp since the weight was negligible but would provide extra power if needed in my case fighting wind and tidal flows. I'm also planning on adding a gen and inverter to the 4 hp and had planned on the long shaft version. I'll use that to top off batteries particularly when New England sun is around less in the fall and spring. I recently looked at electric propulsion but for a 1/4 of the initial cost I'll start with gas power and convert when it becomes cost effective.
Thanks,

Drew - Hampton, NH, USA
PocketShip 'Dreams Won't Wait'
Build Started: Oct 2021
Boat Launched: May 5th, 2023
Build Blog - https://www.dreamswontwait.com
Photo dump = https://photos.app.goo.gl/dS2tViRpgq4YZH8o6
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Re: What Size Outboard

Postby [email protected] on Wed Dec 01, 2021 11:22 am

Keep in mind that some of those up-down-swinging outboard brackets weight 20 lbs. or so.
So if you can come up with a lightweight mounting solution, you will be able to tolerate
a heavier motor.

Also, it looks like the alternator output in 4hp motors is not very large: The Suzuki
is 6 amps, and the Mercury is 4. It will take hours to fully charge a dead battery at that rate.
6 amps at 14 volts is 56 watts: only about 0.11 horsepower, or 2% of the rated motor power.
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Re: What Size Outboard

Postby afairaizl on Wed Dec 01, 2021 12:56 pm

Definitely, it will be a top off in addition to the solar. The slip will be a piece of pavement in the parking pad at the house so it should stay full with 'shore' power where solar/motor help on the water.
Thanks,

Drew - Hampton, NH, USA
PocketShip 'Dreams Won't Wait'
Build Started: Oct 2021
Boat Launched: May 5th, 2023
Build Blog - https://www.dreamswontwait.com
Photo dump = https://photos.app.goo.gl/dS2tViRpgq4YZH8o6
afairaizl
 
Posts: 69
Joined: Mon Aug 02, 2021 12:26 pm
Location: Coastal New England

Re: What Size Outboard

Postby craig on Thu Dec 02, 2021 8:13 am

An interesting community project would be to provide GPS speed measurements at different throttle settings for our individual motor/boat combinations. 1/4, 1/2, 3/4, and full with the speed reached in calm water, no current, and light wind. I have measured that before but can't find my notes currently. I max out with my 2.5HP suzuki at around 5.5 kts, and that was only around 3/4 throttle. Can a larger motor really push Pocketship faster? I thought it would be hull speed limited. If anyone on here has a bigger motor and has experience you should weigh in.
Titania, launched January 2015
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Re: What Size Outboard

Postby Wayne G on Thu Dec 02, 2021 4:23 pm

My original outboard was a 6hp Tohatsu Sail Pro with 25” long shaft which would max out at 5.5knots at about 1/4 throttle. Any more throttle just made noise.

I really liked that outboard but reading other posts on this forum convinced me to downsize and I now have a 2.3hp Honda. The Honda is just under 30lbs compared to the 60lb Tohatsu and it tops out at 5 knots at about 3/4 throttle in calm conditions.

The Honda does the job but I’m sorry that I swapped out the Tohatsu.
Wayne Gray
Orlando Florida
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Re: What Size Outboard

Postby Brent65 on Thu Dec 02, 2021 8:39 pm

Wayne G wrote:My original outboard was a 6hp Tohatsu Sail Pro with 25” long shaft which would max out at 5.5knots at about 1/4 throttle. Any more throttle just made noise.

I really liked that outboard but reading other posts on this forum convinced me to downsize and I now have a 2.3hp Honda. The Honda is just under 30lbs compared to the 60lb Tohatsu and it tops out at 5 knots at about 3/4 throttle in calm conditions.

The Honda does the job but I’m sorry that I swapped out the Tohatsu.



Wayne, did you feel the Tohatsu 6 was too stern heavy? What convinced you to go smaller? What was broken? I plan to use the motor a lot and therefore would love to go with the Sailpro but always thought at 60 lbs, it was just too heavy. Please share your good and bad experiences.

Best,
Brent
Brent Butikofer
Build Blog: http://www.idahopocketship.wordpress.com
Previous Builds: Scamp, Skiff America 20
Never Stop Exploring
Never Stop Learning
Brent65
 
Posts: 48
Joined: Tue Jan 14, 2014 1:55 pm

Re: What Size Outboard

Postby Tom G on Fri Dec 03, 2021 12:00 pm

I started out using a Honda 2.3. I have now changed to a Yamaha 2.5 and really like it better than the Honda for a couple reasons. I did not like the clutch arrangement on the Honda. I mostly use the motor in and out of harbors. When you try to go slow there is a fine line where at low RPM the clutch will disengage and you have to rev it up again. I found that annoying. The Yamaha has forward and Neutral so you can creep along at an idle and just flip into neutral as you approach dock. So for me the slow speed maneuvering was an advantage to be able to just idle and steer with the rudder and not wonder if I'm still in gear.
As for power the Yamaha has a bigger prop and seems to push it along better at lower RPMs than the Honda but I believe either is adequate. ( I used the 2.3 Honda on a 19 Foot West Weight Potter for several years and it was fine for that as well!). I run the Yamaha at about 1/3 throttle and I am moving about at 3.5-4.0. knots consistently. I have never operated at more than about 1/2 throttle even in rough conditions as it seems to me you make more noise , burn more gsa and don't make much more speed. Last summer in Puget Sound, I had to motor 8 miles into about a 20-25 knot wind blowing against the tide. The waves were maybe 3-5 feet and steep faced but it did just fine.
To my ear, the Yamaha is much quieter than the air cooled Honda but your ears may be different!
The Yamaha is about 10 pounds heavier but I'm not convinced it matters much.
In short I can't imagine needing anything bigger than either of these or a Tohatsu 3.5 from a power stand point. Bigger may not mean faster!
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Re: What Size Outboard

Postby Wayne G on Fri Dec 03, 2021 8:20 pm

Wayne, did you feel the Tohatsu 6 was too stern heavy? What convinced you to go smaller? What was broken? I plan to use the motor a lot and therefore would love to go with the Sailpro but always thought at 60 lbs, it was just too heavy. Please share your good and bad experiences.


The sail pro is heavy, I added 50lb of ballast in the bow compartment to balance out the stern load and that worked out well as the forward ballast was below the waterline which helped stability in heavier wind. My main issue with the sail pro was that the long shaft prop dragged in the water whenever the boat heeled. This could have been corrected by adding wedges to the motor mount to counter the transom rake angle to allow the outboard to tilt up higher out of the water.

I do miss the forward/ neutral/ reverse feature which is not just handy for maneuvering it is also much safer if motering in a tight location where other boats are also in motion. The Honda needs to be rotated 180 degrees to stop or reverse the boat.

The sail pro has an external fuel tank which allows longer run time without re-filling and avoids gas spills that can happen when re-filling an internal tank.

Finally, it is very reassuring to have additional power in reserve. The Honda runs at just below hull speed at 3/4 throttle in light wind. The sail pro would comfortably maintain full speed in high(ish) wind with plenty of power in reserve.
Wayne Gray
Orlando Florida
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Re: What Size Outboard

Postby afairaizl on Mon Dec 06, 2021 3:55 pm

I'm assuming the longer shaft outboards at 20" are better than the standard 15" for the PS. I see the sail pro even come in 25" which would explain the issue when heeling. Recommendations for/against 15, 20, 25" based on experience?
Thanks,

Drew - Hampton, NH, USA
PocketShip 'Dreams Won't Wait'
Build Started: Oct 2021
Boat Launched: May 5th, 2023
Build Blog - https://www.dreamswontwait.com
Photo dump = https://photos.app.goo.gl/dS2tViRpgq4YZH8o6
afairaizl
 
Posts: 69
Joined: Mon Aug 02, 2021 12:26 pm
Location: Coastal New England

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