Prop question - Honda 8 on Hunter 26

[Lance14037]

A couple of years ago I changed out my old Tohatsu outboard for a 4 cycle 8 hp Honda. The new Honda runs great, but came with a power prop and at full throttle, I cannot reach hull speed (only reaching a little over 6 kts). My old Tohatsu, also 8 hp got up to 6 1/2 kts at less than full trottle even though it might take many minutes to get there. New Honda has a 4 blade prop marked 10 X 6 1/2 inch. I would like to try another prop to gain more speed (realizing I will give up some power). Does anyone with Hunter 26 or 260 have experience with 8 hp Honda? If so, can you offer suggestions?

 

[JoeWhite]

I used to have a Hunter 25.5 - I assume they are the same size - and I had a Mercury 9.9 and I do not believe it moved much more than 6knots. That is about 7.5MPH. I believe that is the hull speed. In my opinion I would not change the prop as it may stress the gears that are not designed for.

 

[Crazy Dave Condon]

If you are getting 6 hp with the Honda 8, you are about at top max speed for the boat under power. Essentially a four bladed prop gives you more thrust at lower engine speed. I do have one question for you. When you get to the point you cannot go any faster, does the bow tend to start raising up. If you say yes, then you are at max hull speed.

By the way, some of Tohatsu parts are in the Honda engines.

Crazy Dave Condon

 

[soling42]

Hull speed on the 260/26 is 6.43 (+/- a few 1/100th) Our 8hp high thrust Yamaha normally pushes our 260 to about 6.2 with 80% throttle while using about .60gph in fuel consumption. The biggest issue in loosing 1/10kt here or there is more about accumulated weight on board (and too many Christmas cookies for the captain?) along with how clean the bottom is, which is even more critical when sailing than if the motor is running. In preparation of a spring sale I just unloaded nearly 200lbs of cruising pork that had slowly made its way into our stowage so with a good bottom cleaning i'm sure we'll gain back nearly 1/2kt.

I can appreciate trying to get your new motor propped correctly but can't speak for available props for your Honda. Good luck with that 1/2 kt and have a great season, Mike

 

[Lance14037]

Dave, The bow does not raise up. Tohatsu got me faster with less throttle. Honda with 4 blade prop is much better for power around docks, no question about that; but I would prefer the extra speed with less throttle. I don't like running engine at full throttle all the time.

 

[Crazy Dave Condon]

Lance, are you the one that I know personally.

I cannot answer this one but I was always a proponent of Tohatsu which actully makes Nissan and the small Mercurys. Many of their parts are in others to include Honda.

Anyone can help us here now that Lance gave us futher details.

Crazy Dave Condon

 

[Lance14037]

Yes, Dave - I appreciate that you remember me and I thank you for all your help over the years. The Tohatsu was a great engine and you helped make it run better as well. Wanted to change to a 4 stroke plus much work was needed on the Tohatsu.

 

[owner23.5]

I think its that prop you have , I had a 9.9 2stroke tohatsu with stock prop and last year purchased a 9.9 4stroke with power prop of my brother who runs a tohatsu dealership here . I to noticed more speed with the older engine at higher rpm's then the new motor with the powerprop. that new prop works great like you said around the marina /docks but it really SUCKS out in the water . I to had better speed with the standard prop. the powerprop does nothing for my boat after half throttle , full thrttle is the same speed as half throttle with the power prop. I did keep the original prop that came with the new engine. My thought with this whole setup was that I could reach hull speed with powerprop therefore have a quieter ride being I'm only at half throttle, although it is a less noisy ride the power prop is useless once you leave the docks

 

[DJN51]

Don't know if Honda offers but I replaced prop on my 6 hp 4 stroke yamaha with a dual thrust prop.On my 23.5 it backs boat out of at slip at idle,and gain in performance and manuvering at slow speeds was adhanced .Prop is made for sail,pontoon any heavy displacement vessel.

 

[twodzusfittings]

All this talk brings me to the subject of the "The Power Thruster" advertized on this site. I currently have a 9.9 2 stroke Evenrude which as everyone knows is noisy and sups gas at a high rate. If I installed this and the advertized claims are true, this would help with my gas consumption. I am not in the position yet to spend 2-3k and upgrade, maybe in two years. Thought in the mean time I could save by investing in one of these. Anyone on the list currently use on or had any experience?

 

[Crazy Dave Condon]

Last night when I was wondering about the power prop, I think it is designed to push possibly heavy loads but not for speed. I think that is where the confusiion is. I have never recommended the pwer prop.

Crazy Dave

 

[Lance14037]

Thanks to all who commented. After doing some digging, I found that Honda initially sold a choice of two props for my engine. Both are 4 blade - one a power prop 10 X 6.5 and a standard prop 9 1/4 X 8. As Bad Company stated well ... the power prop really SUCKS out on the open water, so I will change to the standard prop.

 

[Quoddy]

Props and more props

We have tried 3 different props and the Power Thruster. The boat is H260, centerboard down, not too much load, with long 9.9 Honda pulling a Zodiac. When testing I would make a run and then reverse course before conditions changed and average GPS speed. Wind and current make a big difference in speed over ground. These observations are over years so they are not direct comparisons.
1 Honda stock prop 9 ¼ x 8-4 blade: best speed for lower rpm, could only reach 4500 rpm, but low speed power limp
2 Honda power prop 10 x 7-4b: better rpm, same speed, good low speed power.
3 Honda low pitch prop 10 x 5-4b: with the two other props full throttle would not reach max rpm. I thought with full rpm full hp could be reached with a resultant increase in speed. Didn’t work. Higher rpm for less speed so more noise.
4 Power Thruster: At low speed, backing down to brake it works great, very little prop walk and lots of power. Overall speed increase or lower rpm for same speed, I would say not. Above 4000 rpm vibration would develop.

Removed thruster vibration gone and speed similar.

Stock: 6.1 k @ 4500 max
Power prop w/o Power Thruster: 6.1k @ 5000 max
Low pitch prop: 5.4k @ 5500 max

Setup now is, Power prop 10x7 w/o Power Thruster, 4500 rpm yields 5.5k at about half throttle, lots more throttle gains little in rpm response. Hull begins to lift way before theoretical hull speed.