What prop are you using? 25/30hp

Big Al C · 28 May 2015, 20:11

Hi, need a new prop for Johnson 2s 30hp. At the moment I have a 10x15x3 on and having fitted a mini rev counter found only to be reaching 4700 at wot, on a bombard 380. That was with 3 up and 40l of fuel,,, plus a bit of gear.
Just would like to know what other 25/30 hp outboards are using on similar size sibs?

Know I need to go down a few pitchers, 10x11 or 10x12? 3 or 4 blade.

Have done lots of reading on the net but would like some fellow sib users advice.

Cheers Al.

dave3235 · 28 May 2015, 20:45

Quote:

Originally Posted by Big Al C

Hi, need a new prop for Johnson 2s 30hp. At the moment I have a 10x15x3 on and having fitted a mini rev counter found only to be reaching 4700 at wot, on a bombard 380. That was with 3 up and 40l of fuel,,, plus a bit of gear.
Just would like to know what other 25/30 hp outboards are using on similar size sibs?

Know I need to go down a few pitchers, 10x11 or 10x12? 3 or 4 blade.

Have done lots of reading on the net but would like some fellow sib users advice.

Cheers Al.

Hi

What is your wot range.Really it needs to be you and lightly loaded boat

Big Al C · 29 May 2015, 00:53

wot is 5200 to 5800,
its not very often I'll be on my own, if I find its to low with a smaller pitch prop I can all ways put 10x15 back on.

dave3235 · 29 May 2015, 10:42

Quote:

Originally Posted by Big Al C

wot is 5200 to 5800,
its not very often I'll be on my own, if I find its to low with a smaller pitch prop I can all ways put 10x15 back on.

Hi

You need to be in the WOT range preferably at the upper end mid way is ok.150 to 200 rpm raise or lower with each pitch.

Roflhat · 29 May 2015, 14:38

We had a tohatsu 30 on the back of a 4.1m Surfcat, used a 10x13p mostly, couldve gone to 14p I think but 13 was good for allround

Big Al C · 31 May 2015, 18:00

Quote:

Originally Posted by Roflhat

We had a tohatsu 30 on the back of a 4.1m Surfcat, used a 10x13p mostly, couldve gone to 14p I think but 13 was good for allround

Cheers for the reply, what sort of load did you have on.

Roflhat · 01 June 2015, 11:48

Quote:

Originally Posted by Big Al C

Cheers for the reply, what sort of load did you have on.

Boat was about 76kg, 25l fuel tank, 20kg anchor and kit bag and usually two people with a combined weight of around 130kg

Would top out at 34 knots

Majotty · 23 June 2015, 16:35

I have a 25hp Mercury 1981, with a new solas 13" pitch stainless on and it is a fantastic all round prop. Would highly recommend. Interestingly I did notice a significant drop in steering torque when I changed to the stainless prop. Not expected but definitely helpful.

So I would recommend a 10x13 stainless.

Matt

Majotty · 23 June 2015, 16:36

Sorry, just realised I failed to mention that I am running the 25 merc on a Bombard 380 aerotec as well. Plenty of power for a full load of people and scary (but fun) with one person!

Big Al C · 23 June 2015, 20:58

Cheers for your info,,,,

Looking like 10x12 or 10x13. 3 blade.

Chris Caton · 23 June 2015, 22:09

Quote:

Originally Posted by Big Al C

Cheers for your info,,,,

Looking like 10x12 or 10x13. 3 blade.

hi, I've got a 10.5 x 13" quicksilver black diamond prop listed for sale in "list your spare props........", only been used once but was under propped with a 50hp on a SR4, I'm after £75 ono

Big Al C · 24 June 2015, 13:26

Cheers, but have found a new stainless steel 10x13 for £99 on ebay.

Neuner · 24 June 2015, 19:40

Please report back on what difference it made on your WOT RPM and overall speed.

Big Al C · 15 July 2015, 23:12

Just got back from a wild camp in Scotland, Loch Linnhe, fitted the Johnson with a stainless steel 10 1/8 x 13 Ballistic prop. New off ebay for £79 plus tenner postage,,,,,

Very similar weight as before, revs are up at wot to 5100 just short of the starting range and the top speed has gone up from 23mph to 26mph.
Back up to Loch Lomond end of the month so will do a retest on my own and min weight.

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Roflhat · 16 July 2015, 12:55

You could try lifting the engine slightly to get more revs, those ballistic props have pretty good bite

dave3235 · 16 July 2015, 13:18

Quote:

Originally Posted by Roflhat

You could try lifting the engine slightly to get more revs, those ballistic props have pretty good bite

Hi all

I have a Ballistic prop on mine,my engine was over reving.Spoke to steel developments and was told going up or down a pitch would change the revs by 250-300 rpm either way,extra cupping would give 500 rpm higher but difficult to take off if needed charge was £63 plus £10 postage each way.As Roflhat says though try raising the engine first see where your revs are.

Big Al C · 31 August 2015, 22:24

Got my dates wrong on the Loch Lomond trip, got back last week.(been very busy)
Some good days out on the Loch and all the island out there, bit of mixed weather but good stuff.

Any way after a day out with the family and back to Milarochy bay camp site, the fuel was down to test levels. Under 10L, so the Mrs and daughter went back to the caravan and I went to play. Off loaded as much stuff as I could, so with the basic stuff, left to try some speed trails.

Using remote set ups, so steering from the front, find this so much better for giving it some stick. Any way,,,,, max out at 28mph with the 10 1/8x13 prop and was pushing 5300/5400

.

May well have got a bit more had I gone for a 10 1/8x12 prop but that was not available for the price I got the 13 pitch prop for. Any way its a good alround prop, well pleased

for the price.

Fstarocka · 30 March 2016, 12:22

Quote:

Originally Posted by Chris Caton

hi, I've got a 10.5 x 13" quicksilver black diamond prop listed for sale in "list your spare props........", only been used once but was under propped with a 50hp on a SR4, I'm after £75 ono

Hi - Im looking for a new prop.. mine spun the hub after my first 30 seconds on water with my new (old) rib..

Im looking at either a 13 or 15".. mine is a 60hp 1987 - current prop is a bog standard 14" 3 blader..

Going to get a merc spitfire 4 blade, not sure if i shd choose 13 or 15.. what pitch did u choose and howd it turn out?

tx

Chris Caton · 30 March 2016, 23:07

Quote:

Originally Posted by Fstarocka

Hi - Im looking for a new prop.. mine spun the hub after my first 30 seconds on water with my new (old) rib..

Im looking at either a 13 or 15".. mine is a 60hp 1987 - current prop is a bog standard 14" 3 blader..

Going to get a merc spitfire 4 blade, not sure if i shd choose 13 or 15.. what pitch did u choose and howd it turn out?

tx

hi, I ended up with a 11" dia. x 15" pitch ally prop, runs fine max 5900 revs and approx 34knts which I'm happy with, i would think a 15" should be good with a 60hp

Fstarocka · 31 March 2016, 05:16

Quote:

Originally Posted by Chris Caton

hi, I ended up with a 11" dia. x 15" pitch ally prop, runs fine max 5900 revs and approx 34knts which I'm happy with, i would think a 15" should be good with a 60hp

What motor were you running? The gearing also plays a big role.. Mines a Merc mariner, at 1.64 bit under geared compared to Yamaha etc.. That's why they recommend the 13.. Using the prop slip calculator the 13 gave better results over all..

http://www.mercuryracing.com/prop-slip-calculator/

Also my wot rpm per manual is 5300.. Punch the numbers and the 13 tops the 15..

Hope it works out!

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