Correct Propeler for honda 10 hp on a 920

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buckle.roger
Posts: 73
Joined: Sat 07 Jun 08, 15:43
Your Country: spain,benissa/alicante

Correct Propeler for honda 10 hp on a 920

Post by buckle.roger »

Can someone please let me know the correst size propeler for a honda 10 on the 920. the standard is well over sized, after half throttle you get no more revs.

i have had no responce to the thread saying they ordered another prop but no info re how it perfomed
buckle.roger
Posts: 73
Joined: Sat 07 Jun 08, 15:43
Your Country: spain,benissa/alicante

Correct propeler for a 920 with honda 10 Hp

Post by buckle.roger »

There have been severalquestions re the correct propeler with no answers.

So i have done some testing.
Conditions, a 920 with a honda 10 hp, just antifoulded and calm sea max wind 5 kns. speeds aveage of 2 runs on GpS. IMPORTANT engine on middle tilt pin, vertical in the water. with a 4 blade alloy honda propeler 10 x 6 1/4

Max revs 5440 at 7kns plus
aprox half throttle 5000 revs and 6.5 kns gives about 1/3 gal/ hour

Stopping test from 4kns = 1/3 boat length

Before this test the engine was pinned on the second hole out and would only give 5.5kns!!!!!!!!!!!!!!
gminkovsky
Posts: 210
Joined: Wed 01 Nov 06, 19:58
Your Country: USA, Long Island Sound

Post by gminkovsky »

what was the size of your original prop?
buckle.roger
Posts: 73
Joined: Sat 07 Jun 08, 15:43
Your Country: spain,benissa/alicante

Post by buckle.roger »

gminkovsky wrote:what was the size of your original prop?
Hi The 10 x 6 1/2 is the only prop I have had, all the figure i gave are for this same prop, When testing with the rpm counter I asumed that I would need a new smaller prop, BUT the engine was not pined correctly hence the 5.5kns.

The way my honda has been fitted , by prievious owner, it is about 3cms higher than it should be as they did not cut the hull/deck jiont in otder to lower the engine fully but it still NOW gives good performance.

Message is to check the pin setting for your engine and if not shure just try other possitions but the engine wants to be vertical to the water
gminkovsky
Posts: 210
Joined: Wed 01 Nov 06, 19:58
Your Country: USA, Long Island Sound

Post by gminkovsky »

I have a standard Quorning-supplied Honda 10 with factory-supplied prop. I don't know the size.

I have no way to measure RPM. To cruise on engine, I turn the throttle to the max, then turn back about 1/4 turn. This gives me average speed of 6.2-6.5 kn over relatively flat water. At this speed, I burn 2/3 - 4/5 of a US gallon (3.8 liter) per hour.

I get more on an empty boat, and less when fully overloaded for cruising. My numbers have been consistent over the last 3 years when I delivered empty boat to/from the boatyard over 20 nm distance and loaded boat to/from cruising destination over 75 nm.

My top speed at FOT is only 6.8-7 kn.

I did more or less accurately adjust the vertical trim.

Your engine appears to be much more efficient.
buckle.roger
Posts: 73
Joined: Sat 07 Jun 08, 15:43
Your Country: spain,benissa/alicante

Post by buckle.roger »

gminkovsky wrote:I have a standard Quorning-supplied Honda 10 with factory-supplied prop. I don't know the size.

I have no way to measure RPM. To cruise on engine, I turn the throttle to the max, then turn back about 1/4 turn. This gives me average speed of 6.2-6.5 kn over relatively flat water. At this speed, I burn 2/3 - 4/5 of a US gallon (3.8 liter) per hour.

I get more on an empty boat, and less when fully overloaded for cruising. My numbers have been consistent over the last 3 years when I delivered empty boat to/from the boatyard over 20 nm distance and loaded boat to/from cruising destination over 75 nm.

My top speed at FOT is only 6.8-7 kn.

I did more or less accurately adjust the vertical trim.

Your engine appears to be much more efficient.
Hi

The prop size is stamped in the hub between the blades.
I got my honda techie to loan me his hand held taco which you just hold near the engine, then all is revealed, however a simple way to know if you are over pitched is to slowly open the throttle and at some point after half thrott;e the rpm will not increase anymore if you are over pitched.
After half throttle you will not get too may mor rpm though, I have remote throttle and after 1/2 I get about 500 rpm more, but before I re pinned the engine after 1/2 throttle I got no more rpm .
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