help prop my zodiac with a high thrust 50hp

[nice-diver]

I have a soft inflatable Zodiac 15 1/2ft. I just bought a Yamaha high thrust 50hp 4stroke.

Now that I know what the motor is, I need it to act like a "normal" motor to push my light weight boat

250#boat
260#motor
2-4 guys
18gal fuel
4-8 scuba tanks and gear

AND just me fishing and cruising

I was told that about any prop from a T50 up to a F130 should fit
I just need some thoughts on where to start
#blades pitch and diameter

thank you

 

[steelespike]

Re: help prop my zodiac with a high thrust 50hp

Is a soft Zopdiac rated for 50hp.My very limited experience with inflatables is they
can run slower than typical hard hulled boats also don't do well with a load.
Also a 15footer will tend to struggle more than a 17 or 18 ft.Inflatables sometimes experience venting issues.
T50 props are available up to 26" pitch.They are about 13 1/4" diameter I'm assuming your motor uses a prop about 13"?
I would run the present prop and get the max rpm and speed.If you get us that info and the present prop size we can help select a prop.
What is the capacity? I figure your at about 1600 lbs total.
I have a feeling it will struggle to plane.A 4 blade may be helpful in that event.And your probably better off with the high thrust. I would guess a 17" pitch to start with.Others with more inflatable
experience may be able to be more specific. With the unique inflatable quirks you might get a prop response in the inflatable section.You will need the specific boat model .

 

[nice-diver]

Re: help prop my zodiac with a high thrust 50hp

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1997 zodiac grand raid 15.5ft; inflatable keel, soft hull
rated for 50hp...65hp max
3000# capacity; weighs 250#, 260#motor
no speed tubes; long shaft

did 25mph with the johnson 40hp

thank you
I will have the T50 running next week

 

[steelespike]

Re: help prop my zodiac with a high thrust 50hp

was 25 with a load?How did it do with a load?It appears that a 40 does over 30 on fiberglass hulled inflatables and hard hulled boats.
Another condition I've seen on inflatables is the motor too low dragging too much through the water.

 

[nice-diver]

Re: help prop my zodiac with a high thrust 50hp

does the same loaded with 2 divers or just me

my first posts here were about depth of motor
the cavitation plate is now at the bottom of the tubes (transom is "higher" than the tubes) now when the boat gets up on top of the water the prop stays in the water the right amount

thank you

 

[steelespike]

Re: help prop my zodiac with a high thrust 50hp

Sound like it may do well with the 50.
I believe your motor has a 2.33:1 gear ratio.The stock 50 Evinrude runs a 2.67.
Uses a 15" pitch on a 1,000lb dry weight boat and a 17 on a 600lb boat.

 

[longshanks]

Re: help prop my zodiac with a high thrust 50hp

Hi

I don't have experience with Zodiacs, but when I put a 50HP 4-stroke on my boat (around 1400-1600lbs, I was getting up to 5800 rpms and 30mph with a 12 pitch by 11" stainless prop. The 4-strokes won't turn as much pitch as the same hp 2-stroke. I'd guess you are going to settle on a 12P prop, possibly a 13P.

good luck!

 

[nice-diver]

Re: help prop my zodiac with a high thrust 50hp

thank you
it took 9 days for 4 tiny carb o-rings, GA yamaha to OR yammy dealer.

hope to put carbs back together tomorrow and get this motor running

[/url][/IMG]this should keep me going with my local source for "clear 92", gasoline not a rock station

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I did this...$0.44 for the clamp and $35 for the plier

 

[nice-diver]

Re: help prop my zodiac with a high thrust 50hp

13 3/8 X 13 high thrust prop did 26mph (garmin gps) max speed 300# boat and just 200#me in boat its tiller control so I don't have a tach reading

the gross weight capacity of the boat is 2800# and I want some speed out of it, so what prop should I start out with??

thank you

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[steelespike]

Re: help prop my zodiac with a high thrust 50hp

You really can't make a proper prop selection without a tach.A Tinytach is reasonable and easy to install.They have a web site.
Without the rpm there is no way to tell if over propped or under, if there is excessive prop slip or for that matter if the setup is right.I wouldn't expect a huge increase in speed from the 10 more hp but it may help when fully loaded.It's possible a prop change will improve speed a little.
A tiny tach for your motor will work on any similar motor without regard to stator poles.Be sure to read all info.It is an induction tach and the wire cant be cut or spliced so must be ordered for you specific needs.

 

[nice-diver]

Re: help prop my zodiac with a high thrust 50hp

thank you
i will work on getting a tach

 

[nice-diver]

Re: help prop my zodiac with a high thrust 50hp

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all on a flat lake

props got some power and does 25 1/2 mph(gps)

 

[steelespike]

Re: help prop my zodiac with a high thrust 50hp

It sure leaps up.I have an 18ft Crestliner utility with a tiller 50 Evinrude.
About 375lbs. With 6 gallons at the bow and a forward deck over the 2 forward seats , my butt against the transom it leaps like that.And it goes fast enough its still a kick even after 60 years of boating.Some day we'll get a tach and a gps so we can figure if its set up right.Its only been about 22 years.
Can you see your antivent plate at speed do you have any venting issues?

 

[nice-diver]

Re: help prop my zodiac with a high thrust 50hp

it was raining so I didn't get any photos of this motor. The tubes sit lower than the transom so there is a lot of spray at the rear of the boat.