5.3 cuddy with a 115 Suzuki

[polyFrank]

Just asking the question on prop sizes. I have a 5.3 cuddy with a 115 Suzuki 4 stroke, with a 3x14x17 prop. There is another number on the prop 27 06 which means nothing to me. (Probably manufacturing date).

I was wondering what props other members have fitted to their motors on a 5.3 poly. I can tell what current is flowing in the Bribie passage when passing under the bridge. So with no wind, no current and the motor trimmed for its best performance. It will at 5000rpm show a speed on the GPS of 45-46 kph.

Just wondering how that fares with other 5.3 poly owners?

[Will]

Hi Frank,

I don't own a poly so can't give an answer based on personal experience but from extensive reading on this site and others it looks like something is not right with your setup. For starters you should be getting close to 6000 RPM at WOT, with the boat lightly loaded. Secondly that top speed (25 kt) is too low - most guys cruise at that speed and max out at 30 - 32 kt (55 - 60 km/h).

If it was my boat I'd probably first make sure that the motor is at optimum height before messing around with prop sizes. Here is a good read about engine height and prop sizes:

http://www.veradoclub.com/smf/index.php?topic=137.0

[polyFrank]

Thanks Will.
I should have stated what my WOT is. I picked 5000 rpm as a sort of benchmark because all motor/prop setups will go faster than 5000 rpm. My motor will rev out to 6300 and do over 60 kph. But I normally run it at 5000.
My previous boats were second hand and I never gave any thought to props. It’s not till I got the owners manual for this motor and read the posts on this forum, that I realized you could change the max rpm/speed of the boat.

I was wondering what props other owners had and with my 5000 rpm cruising revs. Will I get better performance with a different prop.

[Dave]

Frank in the old day, we used to do a lot of water skiing and referred to props as either ski prop or cruise prop.
The ski prop will allow the motor to rev high with a very quick hole shot but you lost a lot of topend speed. (think first gear on a car)
The cruise prop would give you a slower hole shot but better top end speed and cruising economy. (think 3 or 4 gear in a car).
Props that come on the motor as standard are a compromise and give you the best (worst) of both types of prop.

So you need to;

1. Decide whether you want a crusing type prop, a better hole shot or a compromise between the two

2. Save money and stick with current prop if you are happy with the general performance

3. Spend lots of money on a nice stainless steel prop that is custom fitted for your boat. You can do this through the Solas website (http://www.solas.com.au/index.html) or phone Steve and have him work it out for you.

Unfortunately Props aint Props and it is quite a science behind it all...

[geobec]

Amen to that!! Solas is probably the way to go if you want something a little better.

Cheers

Geobec(pirate)

[Will]

Thanks Will.
I should have stated what my WOT is. I picked 5000 rpm as a sort of benchmark because all motor/prop setups will go faster than 5000 rpm. My motor will rev out to 6300 and do over 60 kph. But I normally run it at 5000.
My previous boats were second hand and I never gave any thought to props. It’s not till I got the owners manual for this motor and read the posts on this forum, that I realized you could change the max rpm/speed of the boat.

I was wondering what props other owners had and with my 5000 rpm cruising revs. Will I get better performance with a different prop.

Sorry Frank, I shouldn't have jumped to conclusions. It sounds like the setup you have now is pretty close to optimal, except that the max RPM is a bit above the manufacturers recommended which explains the high-ish cruising RPM. Most guys prefer 4000 - 4500 RPM which gives a good speed/fuel consumption balance.

You can generally get better all-round performance i.e. better fuel consumption, top end and hole shot by fitting a stainless prop customised to your boat/motor. However it costs a fair bit to do and if the prop you have now is already close to the mark then the improvements won't be spectacular. So it's a question is, is it worthwhile spending $1000+ to get that last few % improvement? As mentioned by Dave, give Steve at Solas a call, he knows his stuff.

[polyFrank]

Thanks guys, I won’t be buying a S/S prop. My original post should have said “ 5.3-115hp combo, what size prop do you have fitted?” I made it to complicated.

I will get my next service done at Cunningham Marine. They are my nearest agents for Polycraft, so they should be able to tell me what prop should be on my motor.

[Dave]

Frank if you are going to go to a dealer (and I'm not picking on any dealer in particular) make sure they know what they are talking about.

It wont hurt to ring Solas for info anyway. You dont necessarily have to buy a SS prop.

[polyFrank]

Had a look at the Solas website Dave and your right. Getting their advice and one of their props is the way to go.
Thanks.

[polyFrank]

Solas recommended a four blade S/S prop for my 5.3 Poly/115 Suzuki. Cupped to 18p whatever that is. I have placed an order for one and at $650 it seems good value. The motor needs a service so I will get them to fit the prop for me.

[Will]

That seems quite reasonable Frank. Let us know what figures you get.

If you're so inclined, have a read of this regarding props. I found it very informative.

http://www.30plus.org/Chief_Plasma/propellers.pdf

[squizzytaylor]

Solas recommended a four blade S/S prop for my 5.3 Poly/115 Suzuki. Cupped to 18p whatever that is. I have placed an order for one and at $650 it seems good value. The motor needs a service so I will get them to fit the prop for me.

If its not right you will find the Solas boys will be happy to exchange it anyway, just send the old one back and they send a new one to you.

GT

[Giffo]

Gday Squizzy,good to see you are still hanging around the site.

[polyFrank]

I did read that info on props Will. Now I know what cupped is.

[Nemo]

Hi PolyFrank,
I visited steve at boatshow last year and bought two four blade s/s props, one for me and one for brother in Gladstone with same motor/boat etc. Got 13x19 with "extra cup"
Steve was very helpful, brother ran his into gravel bank and sent back for reapirs with no issues.
Can't attest to any noticable increase in performance etc but aluminium prop on boat when I got it was filed down to remove dings, so it is now spare prop. I'm sure new prop is at least as good if not better, but I'm not that "in-tune" with boat motor to notice difference. Tried to do some measurements when changing over but couldn't determine much diff in speeds at different revs, but was going off dial tacho and old chartplotter not anything too precise or repeatable. Still happy with prop for around $650.