Hi Graham,
If you're going to order a new prop from the USA, please let me know!
I'm sure we can get a discount on shipping if we order two...
Daz.
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| Hole shot improvement from mercruiser 190hp https://www.smwebhead.com/phpBB3/viewtopic.php?f=2&t=10852 |
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| Author: | Liquidenoir [ Wed Jan 09, 2013 1:23 am ] |
| Post subject: | Hole shot improvement from mercruiser 190hp |
Having no knowledge of props, I need to improve the hole shot performance. Motor is only 12 months old and has the standard 14 x 23p three blade aluminium prop. Put a couple of larger adults on the back seat and she struggles for a while. High speed not as important as mainly used for cruising and water sports. Should I be looking as a 14 x 21 four blade (s/s) ? Cheer. Graham |
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| Author: | rpengr [ Wed Jan 09, 2013 11:37 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Certainly, reducing the pitch will increase hole shot. I would try a 3-blade 14 x 21 or even a 3-Blade 14.25 x 19 Going to a 4 blade might be an advantage or a disadvantage. I think going to a larger diameter, or a 4 blade is likely to be a disadvantage on a 190HP, but look for others experience with the same boat & engine/drive. You WANT a certain amount of slippage during the hole shot, so that if you jump to full throttle, your RPM can jump up to the middle range where your engine puts out adequate torque and power (say 3000+ rpm?). If you hit full throttle and your RPM only jumps to something like low-2000s rpm, then you won't get much acceleration at all. You don't need a larger diameter (or more blades) unless you are tending to over-rev during acceleration. |
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| Author: | deafwish [ Wed Jan 09, 2013 3:26 pm ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Are you able to achieve max RPM when trimmed? |
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| Author: | Surface Interval [ Wed Jan 09, 2013 7:33 pm ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Most four Winns boats in your general size use a 14 1/4 inch diameter prop, and you may also occasionally see a 14". Some older boats and many cuddys or 20 - 30 foot cruisers may use a 15 inch diameter prop or larger, or a duoprop drive. Several things can affect prop selection including engine power, boat type and weight, boat loading, type of prop, and gear ratio of out drive. The engine and boat manufacturers generally recommend being able to get within 200 rpm of redline to achieve the overall best balance of performance. Better slow speed acceleration means higher rpm at all speeds and usually less top speed. Some boaters will use a lower pitch prop to get better acceleration while others will choose a higher pitch prop for better cruise performance and fuel economy. Going to a four or five blade may help on some boats, but remember that the more blades or blade surface the more drag or resistance. As rpengr said, you want some prop "slip" to allow the engine to rev up into its maximum torque range for better acceleration. Generally speaking 1 inch of pitch usually equates to about 150 - 200 rpm at top speed. I believe that a quarter inch larger diameter also makes something like 200 rpm difference. The "cupped" blade trailing edge can make about 200 rpm difference. Different brands and models of props, even though they are the same diameter and pitch, can give different results. Some stainless props might do better than aluminum, but not always. You may gain some improvement in your desired performance, but prop selection is usually a compromise, ....and some what of a trial and error process. best of luck. |
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| Author: | purdueosch [ Wed Jan 09, 2013 10:29 pm ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Graham, As the others have suggested, changing out the prop should help. Just for something else to think about, I've seen a few smaller (18' - 22') boats benefit from adding a hydrofoil. One boat in particular did so well with the hydrofoil that I started considering it for my 24' cuddy until I sold it recently. I think my cuddy would have benefited from trim tabs more, but who knows at this point. It's just a suggestion, I'm not a boat expert by any means. Take care |
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| Author: | Liquidenoir [ Thu Jan 10, 2013 2:23 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Thanks all for the advise. Not having the boat with me, I'm not sure if it's a 14 or 14 1/4. Has no problem reaching max rpm (probably around 4900) With hole shot full throttle, pulls around 3,100- 3,200rpm Sounds as if the three blade 21p aluminium would be the first option. (and most economical) Also gives me a spare prop ! Any other advise most welcome. Good prop manufacturers ?, preferably Australia. |
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| Author: | rpengr [ Thu Jan 10, 2013 8:28 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Liquidenoir wrote: Thanks all for the advise. Not having the boat with me, I'm not sure if it's a 14 or 14 1/4. Has no problem reaching max rpm (probably around 4900) With hole shot full throttle, pulls around 3,100- 3,200rpm Sounds as if the three blade 21p aluminium would be the first option. (and most economical) Also gives me a spare prop ! Any other advise most welcome. Good prop manufacturers ?, preferably Australia. Those numbers sound pretty good, but yes a three blade 21p aluminum would be what I would try first. I don't mean to state the obvious, but your best hole shot is with the drive trimmed all the way down. Then you can trim out once up on a plane. Also, on my previous boat (20' cuddy), if I had more than 4 adults, I had them move forward to get on a plane, then they could go to the rear seats after on plane. |
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| Author: | Aussie_Horizon_190 [ Thu Jan 10, 2013 7:22 pm ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Check out the option of buying a prop from the US - there are some good prices at the moment as it's the middle of their winter. I have found buying them locally is more than twice the price! I have bought quite a few this way (including genuine VP and Merc) and saved heaps. Try http://www.getaprop.com or similar web sites. Also try http://www.marinepartsexpress.com for a genuine Merc or Volvo one... |
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| Author: | deafwish [ Sun Jan 13, 2013 3:01 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Hi Graham, If you're going to order a new prop from the USA, please let me know! I'm sure we can get a discount on shipping if we order two... Daz.
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| Author: | Liquidenoir [ Tue Jan 15, 2013 2:33 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Hi Daz. Will do if I go ahead with that idea. Have read up un the se300 hydrofoil and the reviews are generally very good on my size boat. Might try that first and then go for the prop idea. If I get time before the weekend, will fit one and try it out at Eildon. Will let you know how it goes. Cheers. Graham |
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| Author: | deafwish [ Tue Jan 15, 2013 3:14 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
If a manufactured cost of a hydrofoil style item ($30?) made such a significant performance impact, both Mercruiser & Volvo Penta would fit them as standard. You'll get much better bang for buck with the correct prop. I don;t know if you have a Volvo, but I have a Volvo Penta 14x21 if you'd like to borrow it for testing? Daz - Notting Hill, VIC <edit> You have a Mercruiser! 
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| Author: | rpengr [ Tue Jan 15, 2013 3:21 pm ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
deafwish wrote: If a manufactured cost of a hydrofoil style item ($30?) made such a significant performance impact, both Mercruiser & Volvo Penta would fit them as standard. +1 I had a "Dole Fin" hydrofoil on my previous boat... the one I already mentioned had trouble getting on plane with adults in the back seats. |
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| Author: | Liquidenoir [ Wed Jan 23, 2013 5:18 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Installed the SE 300 hydrofoil and what a difference. Pretty well eliminated bog down with 5 in the boat and one on a single ski. Well worth the money. Will still change the prop when I have the time. I'll let you know Daz. |
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| Author: | deafwish [ Wed Jan 23, 2013 6:53 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Interesting!  Can you plane at a lower RPM? Have you lost any RPM? p.s. I ordered a Solas Amita 4, 14X21p and hope to get it within a week.
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| Author: | Liquidenoir [ Fri Jan 25, 2013 5:34 am ] |
| Post subject: | Re: Hole shot improvement from mercruiser 190hp |
Hi Daz. Plane at lower rpm--yes Still sits around the 3100-3200 on hole shot. Never got the chance to try wot. Have to wait till no scared passengers. Interested to see how your new prop goes. Graham |
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