Honda 50 - prop?

TonyC · 18 November 2008, 19:24

I just want to get some thoughts from others on here about our rib

We have a honda 50hp on the back, and WOT atm only produces about 4500-4700 rpm (manual says max range is 5500-6000rpm)

It currently has a standard 13in prop on it and I know that if I drop the prop size, it should increase the revs, but is this the only option? (12in prop seems a bit small to me?)

Nos4r2 · 18 November 2008, 21:10

Whats the boat?

Downhilldai · 18 November 2008, 21:12

If you provide a bit more information, people may be able to help.
e.g.
What boat is it?
What loading when you get restricted max RPM?
Has it always been like this?
What age/hours on the engine? Has it been serviced recently?
Is the propeller in decent condition?

I could ask another dozen questions, but these should be good for a start.

TonyC · 18 November 2008, 21:28

It's an XS 5m. Loading isnt coming into play, as whether its one up, or four up, it's the same.

It's been like it since it was married with the boat. Engine is a couyple of years old, but only had minimal hours & use put on the engine before being put into storage. Since going on this boat, its had about 120 hours on the engine.

The engine was serviced in April when it was taken out of storage and put on the RIb, and the prop is in near perfect condition.

Downhilldai · 19 November 2008, 00:12

Strange that it's not making more max RPM when lightly loaded.

Is the motor getting max throttle on the carbs? Perhaps the throttle cable needs adjusting?

jyasaki · 19 November 2008, 16:50

How does it get up out of the hole?

You're about a thousand rpm low; if it's only the prop, you'd think it would take forever to get on plane.

FWIW, my buddy is running a 16' Zodiac RIB with a Merc 60 4-stroke, and runs a 12" 4-blade SS prop.

jky

TonyC · 19 November 2008, 17:04

Gets up on the plane just fine, revs arent noticibly different when a few up (dont think ive ever had it fully loaded)

Thats sort of why I was wondering. in general the boat seems to perform just fine with the current prop at the revs it reaches, im just wondering if it could be something else.

jyasaki · 20 November 2008, 17:13

First thought: I'd be looking at the throttle control not fully actuating the throttle at the motor.

Should be fairly easy to test: Pull the cover, see what moves when you change the throttle position, set to WOT, and see if you can move the parts more. You can verify by doing the same thing on the water (have someone else move the part, or steer the boat - not a one-man job.)

jky