Another prop question...

[JohnOD]

Folks I need some suggestions as to the proper replacement prop for my aluminum boat. I believe I am currently overproped as the hole shot is sluggish and the tach reads 4800 max @ WOT. The top speed is fine, what I want is to be able to get on plane more quickly. Last weekend I was running 29 MPH with me, gear & a full tank of fuel. Later in the day I added two additional anglers and a heavy cooler and could not break 13 MPH :whazzup:.

I suspect that the dealer I purchased the new boat/motor/trailor package from this spring did not make much of an effort to get me propped correctly. FWIW his shop is located at sea level, he didn't know what elevation the boat would be running at.

Here are the particulars…

The boat is 17 ½’ aluminum North River revenge which is rated for a maximum of 60 HP.
http://www.northriverboats.com/models/all/specs.php?productid=5

Honda 50 HP tiller 4-stroke currently with an aluminum C3x11.1x14 factory prop, Hondas recommended RPM range is 5500/6000 RPM so I’m running about 1000 RPM low.
Loaded weight is 1400/1500 lbs empty (not including me & a passenger or two).

I’m running the boat at elevations of 4500'.

Thanks in advance, John

[D-tangle]

I went to a dealer and told him my 21 pitch prop was sluggish and WOT was 4200. He got out a prop guide, figured my weight boat, the hull type, the WOT range (5200-5800) and re-pitched me with a 15 pitch prop. Works great. Now i have quick hole shot, plane quickly, and hit 5300 WOT, where it should be. Talk to a boat dealer that knows his stuff. I have the 21 pitch prop under the seat as a back-up.
Good luck.

[Chrome Bumper]

I think the rule of thumb is 500 RPM per inch of pitch, so you want a 12 inch pitch to add 1000 rpm. You may want a range smaller main jets to to get the mixture right, but above sealevel you won't get rated HP.

Those fins you put on the motor cav plate might help, but IMHO those just compensate for poor loading.

If you want to get max life out of your engine and optimum mpg with a light load you are propped great, for more weight decrease the pitch.

You can google up the parts.


My little honda seemed to run lean out of the box at sealevel. I think they may do that to keep the emmissions down. I will fool around with the jets soon, does your motor have a throttle stop you can adjust for more throttle? Mine did and backing that out helped. I doubt your's does though.
Tiller says to me your weight might be to far aft maybe, a dolfin type thing may help.

Smaller jets are needed at elevation due to thinner air(your motor is carbarated I assume). 4500' might not require it though. That's about $5 bucks a carb, prop about $75 for a new aftermarket DIY. Being new all the gaskets should be reusable.

I would change the prop and chack the sparkplug color to see if the are burning at the right temp., they should be kinda tan colored. Having an extra prop is a good thing.

That boat and motor should be a good match, not lightning fast, but cheap to operate and should make fair speed.

[crabbait]

In my humble opinion, the folks who sold you that boat/motor combination did you no favors at all.

The controlling factor for power on the back of your boat is engine weight. Honda has got to be about the heaviest 4-stroke out there and they only sold you a 50hp when you are ratedd for 60hp, and every pony counts with a 17' boat at 4500'. First problem: You are under motored. This is not that uncommon. Salesman want you in the boat and will say that a 17' boat and a 50hp Honda are a good mix. Now you know differently.

Second, you are over-propped. You need to be able to get the motor up to the lowest rpm rating recommended by the factory or you can do some bad things to the engine. You need the biggest prop that the motor will trun to recommended rpm and I would strangly recommend stainless; you need every bit of power you can get out of that thing.

Lastly, you need to be very spartan with weight. Amything that you don't need on the boat should be offloaded, otherwise, she just won't plane.

It is my understanding tha the charts that the Coast Gaurd uses to determine max horsepower are out of date (controlling factor is the heaviest weight 4-stroke for a given horsepower). Compare engine weights for Suzuki v. Honda for any given hp and see what you find.

[ICHTHYDEMON]

You definately need less prop. I used to have a 17' Alumaweld SuperVee with a 50HP Yamaha on it. I was running a 10 3/4"x12" aluminum prop and with 3 guys and gear could run up near 30mph. It also got on step easily with the same load.

[Mister G.]

John OD,
I have a 17 1/2 Revenge with a Honda 50. Mine's a windshield model (for whatever weight diffeence that might make) I get 29 mph @6,000 rpm, two aboard with normal gear, and full fuel (27 gal) My prop is a 13" and has no trouble planing this load.

Crabbait,
WADR, Honda makes the lightest weight 50HP in the marketplace. Haven't checked other HPs/Mfgs.

DB

[Chrome Bumper]

A stainless prop is more effecient and more likely to break your lower unit if you strike debris where aluminum prop is more likely to break, sparing the lower unit. If you think you might hit a rock, log or other debris go aluminum. I only use stainless in blue water.

50 HP is plenty to plane your boat. The only question is what is the your lowest acceptable top speed, if you are happy with 25-29mph you are good to go. Most people are impatient and want more speed and would go nuts cruising at 25 mph.

If you move weight forward and are still tail heavy one of those doelfin type things does help.


Sounds like drummerboy has the ticket, with a third guy, a cooler and considering the elevation you may want a 12 pitch, but you may lose some top end. How often you got the third guy? Let him buy the 12" prop. Get your self some extra hardware for holding the prop on too, nut washer, etc., in case you drop a piece in the water swapping props.

I wonder if Drummerboy has a steering wheel which would put the operator's weight forward more, helping the weight distribution.

Fooling around with the prop is way cheaper than more HP and the gas to turn the extra engine displacement.

[Starfish]

I don't think you'll lose any top end speed by dropping to a 12" pitch prop; in fact you'll likely pick up some speed by letting the motor rev up into its powerband a little better. Most importantly, you will prevent damaging the motor; running an overpropped motor can result in overheating, shortening its life. You should see a major improvement in performance by re-propping. You may even end up going lower than 12 pitch.

You'll normally see me strongly advocating stainless props, but for a 50 hp tiller application I think you'll be plenty happy with aluminum. I doubt you'd see more than a mile per hour difference.

I doubt if you'll have much improvement from rejetting, since that Honda is probably tuned to run pretty darn lean to begin with; running at 4500' will make it run rich, so you could lean it out a bit if you wanted to, but then would need to rejet if you ever dropped back to sea level to keep from overheating. I'd rather err on the rich side unless you're fouling plugs.

[crabbait]

drummerboy - You are correct, Honda is the lightest 50hp at 212lbs (Suzuki-243lbs, Merc-248lbs (50 and 60hp)).

Chrome - The sacrificial hub protects the lower unit on an SS prop. The "hit something and break the lower unit" is not-so-much true.

[JohnOD]

Wow thanks for all the input folks!

ICHTHYDEMON & Drummerboy If I may ask what elevation are/were you running your 50's with 12/13" pitch props at & getting that kind of performance? If it was lower elevations level perhaps an 11" would be best for me. Top end is not as important to me as being able to get on step quickly with a heavy load.

Crabbait I agree with you on the underpowered & overproped assessment. The dealer wanted to set me up with a 25HP but I bumped it up to the 50. I’m not going to change out the motor any time soon. Unfortunately removing weight from the boat is not an option due to the way I use it. Sometimes I have three anglers + me in the boat. Yes it is a heavy pig with three batteries, a bow mount Minn Kota, etc.

I did check the spark plugs and they look fine.

I regularly fish Crane Prairie Res & already had to have my prop straitened once this spring due to hitting a submerged snag. Maybe a Stainless prop would hold up better, don’t know but I like the cost of aluminum a whole lot better.

John

[ICHTHYDEMON]

Wow thanks for all the input folks!

ICHTHYDEMON & Drummerboy If I may ask what elevation are/were you running your 50's with 12/13" pitch props at & getting that kind of performance? If it was lower elevations level perhaps an 11" would be best for me. Top end is not as important to me as being able to get on step quickly with a heavy load.



John



I typically run at sea level,as I live just a couple miles from Puget Sound. We do spend alot of time at a lake thats at 3500' and still had plenty of power for my needs.

[Mister G.]

John OD,
I run in the Ocean (on REAL calm days), up to Detroit Lake and Green Peter. Havn't been at any higher elevations.

Chrome,
Yes, I have a steering wheel. Both myself and crew sit forward to balance. I didn't mention before the 5HP kicker and extra 3 gallons of fuel in the spare tank. That does stick another 75 lbs. or so aft. I'm sure I would not get thesame performance with three guys and gear (and hopefully fish) onboard. For my needs, though, I do think I have this rig pretty well dialed-in.

DB

[Chrome Bumper]

drummerboy - You are correct, Honda is the lightest 50hp at 212lbs (Suzuki-243lbs, Merc-248lbs (50 and 60hp)).

Chrome - The sacrificial hub protects the lower unit on an SS prop. The "hit something and break the lower unit" is not-so-much true.



IMHO SS props tend to wreck bearings and bend shafts. The SS blades bend and fold rather than snap off clean like on aluminum props. The rubber hubs can only spin and only relieve torque, not bending overloads, like when you hit a solid object at speed.

I vote for a 12", is the weight of the batteries forward?

[BassinFever]

You are asking that little 50 HP to handle a rather large job. I hate it when dealers sell underpowered boats to unsuspecting people. 17 1/2' boat, with a kicker on the back fully loaded should have at least a 90 HP on it. You will need in the neighborhood of a 10P prop to get any kind of a hole shot. Forget the fin on the engine, take a look at these first.. They are the best product I have ever seen and would work wonders for your boat.

Smart Tabs made by Nauticus.

[Chrome Bumper]

Yea trim tabs are better than the fin thingy, more boat bucks too.

Going from a 14 to a 12 will make a huge difference.

Tacoma propeller has a 12 pitch 11.75 Dia 3 blade al factory match, thats my bet. Down on the pitch and a hair bigger diameter. They sound pretty helpful. The local shops may have a reconditioned one on hand for a couple bucks less.

Shift all the heavy stuff foward that you can. Several decades ago a 50 was a pretty big outboard.

[JohnOD]

I appreciate all the input folks. One of the local shops set me up with a 12 pitch that I can return for a different size if I don’t like it. It's got to be better than the 14 I'm running now.

If the new prop doesn't give me the performance I'm hoping for I'll look into the smart tabs.

Thanks again, John