Propeller selection info and speeds

jhnmdahl
Vice Admiral
Vice Admiral
Posts: 378
Joined: Tue Jan 06, 2015 5:11 pm
Location: Twin Cities, MN

Propeller selection info and speeds

Post by jhnmdahl » Mon Jul 13, 2015 10:54 am

I wondered for a while why my 210 with a V8-225 was slower than the V8-225 tested by boattest.com (see http://www.boattest.com/engine-review/V ... 8-225_2013), but couldn't even find reliable info on propeller pitch until I stumbled across this document:

http://www.pentamarine.co.th/pdf/propellers.pdf

It pretty clearly shows the difference between the FH4 propellers on my boat and the FH6 propellers on the similarly-sized test boat, and accounts for most of the difference in observed performance. It does make one wonder why Cobalt chose the FH4 set instead of FH5 or FH6, but perhaps the outdrive has a different reduction ratio?
Administrator of the www.cobaltchat.com Cobalt boats community forum

liquid
Vice Admiral
Vice Admiral
Posts: 332
Joined: Mon Jul 20, 2015 2:18 pm
Location: Rochester, NY

Re: Propeller selection info and speeds

Post by liquid » Fri Aug 28, 2015 10:06 am

This is an interesting topic. Again I've done some pretty exhaustive research on if I should upgrade or switch props - Mine is an SX Single prop so not quite the same issues as the Duo Prop - but I did find the Volvo Penta page which discusses all the different drives and prop configurations.

here it is: http://www.volvopenta.com/volvopenta/gl ... rives.aspx

My question is should I upgrade to a Stainless prop? Switch from a 3 blade to a 4? I'm not interested in top speed - just smooth ride and water sports.

There's a prop guide on there but it's still pretty confusing all told trying to figure out if you should go original manufacturer or aftermarket, pitch etc. Any feedback would be great - seems like it's just John and I talking back and forth lately...

Also here's a pretty cool explanation of the difference in the volvo's and Mercs:

http://www.hoffmasters.com/power.html
2002 190
5.0L Volvo Penta GL

jhnmdahl
Vice Admiral
Vice Admiral
Posts: 378
Joined: Tue Jan 06, 2015 5:11 pm
Location: Twin Cities, MN

Re: Propeller selection info and speeds

Post by jhnmdahl » Fri Aug 28, 2015 2:32 pm

That is a nice page regarding the Volvo and Mercury engines. Cobalt was kind enough to send me a prop/engine chart for the 210, which sheds a little more light on the story:
210props.jpg
210props.jpg (188.05 KiB) Viewed 824 times
Administrator of the www.cobaltchat.com Cobalt boats community forum

Big Block Power
Admiral
Admiral
Posts: 714
Joined: Sat May 07, 2016 8:05 pm
Location: Neenah,Wi

Re: Propeller selection info and speeds

Post by Big Block Power » Wed May 18, 2016 8:27 pm

liquid wrote:This is an interesting topic. Again I've done some pretty exhaustive research on if I should upgrade or switch props - Mine is an SX Single prop so not quite the same issues as the Duo Prop - but I did find the Volvo Penta page which discusses all the different drives and prop configurations.

here it is: http://www.volvopenta.com/volvopenta/gl ... rives.aspx

My question is should I upgrade to a Stainless prop? Switch from a 3 blade to a 4? I'm not interested in top speed - just smooth ride and water sports.

There's a prop guide on there but it's still pretty confusing all told trying to figure out if you should go original manufacturer or aftermarket, pitch etc. Any feedback would be great - seems like it's just John and I talking back and forth lately...

Also here's a pretty cool explanation of the difference in the volvo's and Mercs:

http://www.hoffmasters.com/power.html
Did you ever change props? I'm a huge stainless prop fan. But do you know your water have you boating for quite awhile. If so move up you won't regret it.also for water sports 4 blade is the way to go. My buddy is about to try out a merc rev 4 17pitch on his sx drive with a 5.0gxi.on his 2004 cobalt 200. I'll report back how that worked
2003 Cobalt 220 8.1gxi
Neenah Wi

liquid
Vice Admiral
Vice Admiral
Posts: 332
Joined: Mon Jul 20, 2015 2:18 pm
Location: Rochester, NY

Re: Propeller selection info and speeds

Post by liquid » Fri May 20, 2016 11:51 am

I have not changed yet. I want a stainless prop i just haven't decided which one etc... I welcome suggestions.

I also am a little sneaky when it comes to buying new things for the boat. The boss (wife) spends $ on whatever she wants and I never say a thing - I buy anything and there's a conversation involved.

I just added the second battery so may hold off on the prop for a bit... gives me time to do insane research.
2002 190
5.0L Volvo Penta GL

Big Block Power
Admiral
Admiral
Posts: 714
Joined: Sat May 07, 2016 8:05 pm
Location: Neenah,Wi

Re: Propeller selection info and speeds

Post by Big Block Power » Fri May 20, 2016 8:47 pm

If it was a merc I would be all over this. sorry if you already posted this info. But what is your wot speed and rpm. I think you said you wanted it for water sports mostly. Do you know your gear ratio? It's on the tab on the drive. What prop is on it now? Pitch and diameter helps. And yes it's a aluminum. We have had great luck with the rev 4 but a 5.0 might have trouble turning that big prop. I loved my high five also. I tab a vensura. But ask with a 350 mag.Yes you can run a merc prop on a Volvo. I'll know tomorrow how that works on my buddies 200. He has the 5.0gxi though running a 17p rev for the first time. He took of a aluminum but it was way over propped and could only get 4000 rpm out of it.He wasn't sure what pitch it was. He just bought the boat.
2003 Cobalt 220 8.1gxi
Neenah Wi

liquid
Vice Admiral
Vice Admiral
Posts: 332
Joined: Mon Jul 20, 2015 2:18 pm
Location: Rochester, NY

Re: Propeller selection info and speeds

Post by liquid » Mon May 23, 2016 10:54 am

Engine is a Volvo Penta 5.0L GL. WOT range is 4400-4800 RPM. Gear ratio is 1.51 / 1.6.

Here's a good link if anyone else wants to check their info - ***Always confirm these are correct, don't assume!***

http://www.rubexprops.com/boat-propelle ... make=Volvo

As far as what is on there now i don't know... It's definitely aluminum and definitely worn and a little bent.

I know the waters where I boat very well - However, that didn't stop me from chunking a nice stump last summer in a spot I should've been clear.

Problem I have is I'm now about to begin exploring some new waters (new lakes etc) and while an aluminum prop means less performance it also means more forgiveness. I'd hate to get a brand new stainless, wack something and hurt the drive. This is unlikely but a concern.

So the real question then is 3-4 blade... My kids are young - 3 and 4 so they don't do much, yet. Basically dragging them around on a tube. That'll change quickly I'm sure as they get older. As for us I could honestly care less about top-end speed. Honestly can't ever think of situation where I'd need to go over 40 MPH for anything. I've never fully opened her up... I think I backed off around 45, although she definitely had more to go.

So i guess it's really getting to plane and cost. Again, I welcome all suggestions.

Sidenote - took her out first time this year yesterday. Lake was glass. Spent the day chasing the sun around the clouds and not worrying about listening to music because of the 2nd battery.
2002 190
5.0L Volvo Penta GL

Big Block Power
Admiral
Admiral
Posts: 714
Joined: Sat May 07, 2016 8:05 pm
Location: Neenah,Wi

Re: Propeller selection info and speeds

Post by Big Block Power » Mon May 23, 2016 4:17 pm

Well a stainless is four giving also as they don't bend and chip as ready either when they hit something. They also have a rubber or hub to protect the prop shaft. But yes damage can occur with either.lol I would go stainless 4 blade. The rev 4 prob 29 or 17 pitch is great. My buddy can't get his running right yet.We think the good old Volvo fuel pump is taking a crap. I'll try to get him on this forum too. I can't he'll on performance with Volvo props I've never used them. Everyone with a merc and alpha drives love the rev 4 I loved mine.it was a rocket out of the hole no matter how many people were in the boat. I'm thinking of switching my dp for hills 4 blade set ups.
2003 Cobalt 220 8.1gxi
Neenah Wi

jhnmdahl
Vice Admiral
Vice Admiral
Posts: 378
Joined: Tue Jan 06, 2015 5:11 pm
Location: Twin Cities, MN

Re: Propeller selection info and speeds

Post by jhnmdahl » Mon May 23, 2016 8:14 pm

The usual recommendation seems to be keep trying more and more pitch until you can't reach full engine rpm anymore, then back off to the last propeller that let you get full engine rpm. This requires a helpful dealer who will send you out with a few propellers knowing you'll only buy one, or who will swap them for you at their marina in hopes of making a sale with their great service.

I'd also mention that aluminum propellers not only wear somewhat faster than stainless, they can also flex a bit under load (depending on alloy). I do like stainless props, but I've already made one trip to the local propeller repair shop (propmd.com) to have my stainless duo props fixed, and am now more diligent about avoiding unknown shallow water.
Administrator of the www.cobaltchat.com Cobalt boats community forum

Big Block Power
Admiral
Admiral
Posts: 714
Joined: Sat May 07, 2016 8:05 pm
Location: Neenah,Wi

Re: Propeller selection info and speeds

Post by Big Block Power » Mon May 23, 2016 9:04 pm

It's not always right but my rule of thumb was if you had a 21p alum you could drop to a 29 stainless and get the better hole shot but because it's stainless and it holds the water better and doesn't flex you maintained the same top end if not more. Changing from 3-4 blades is a bit different.
Also having two batteries is a plus. I've only had one boat with that set up. My last boat I could listen to the stereo for hours and no issues. But I keep this small compact battery jump pack with the boat just in case and yet to use it. I was lucky I bought common props on cl so of I didn't like them I could resell them. Then I finally found a few that worked. I think I paid a max of $300 on one.
2003 Cobalt 220 8.1gxi
Neenah Wi

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest