Propeller selection info and speeds

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jhnmdahl
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Propeller selection info and speeds

Post by jhnmdahl »

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?
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Re: Propeller selection info and speeds

Post by liquid »

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
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Re: Propeller selection info and speeds

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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
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Re: Propeller selection info and speeds

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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
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Re: Propeller selection info and speeds

Post by liquid »

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.
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Re: Propeller selection info and speeds

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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.
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Re: Propeller selection info and speeds

Post by liquid »

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.
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Re: Propeller selection info and speeds

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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.
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Re: Propeller selection info and speeds

Post by jhnmdahl »

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.
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Re: Propeller selection info and speeds

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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.
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Re: Propeller selection info and speeds

Post by liquid »

It seems to me that in 2016 trying several props and hoping your local marina will work with you is a subpar system.

My local Cobalt dealer/marina are amazing - I think it has a lot to do with local clientele understanding what they're paying for and the marina understanding exceptional service is paramount.

That being said it seems logical that 2-3 prop setups for each boat/engine configuration should be pretty standard by a knowledgable dealer... Amiright?
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Re: Propeller selection info and speeds

Post by Big Block Power »

Sorry that should have been a 19 pitch stainless not a 29. Crap that would be funny watching you try to spin that.lol sorry. I think
b blades have a prop program you could check out.
Yes the dealer should know but we try so many different props ourselves it did help to hear what we are really having good luck with. Last year I brought a rev 4 to the prop repair shop and he is like wow I don't see this prop very often. I'll tell you the merc guys on another forum swear by it and so do I. Every boat and every prop is do so different even if they are the same make and model and pitch.No two are the same.
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Re: Propeller selection info and speeds

Post by liquid »

Welp, took a nice chunk out of the prop (pulling onto the trailer i think) - so looks like I'm getting that new prop sooner than I thought!

Noticed going through my checklist launching on Memorial Day. She still drove fine but now I have an excuse!

4 or 5 blade? pitch for 5.0 GL?

Love to hear all suggestions.
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Re: Propeller selection info and speeds

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liquid wrote:Welp, took a nice chunk out of the prop (pulling onto the trailer i think) - so looks like I'm getting that new prop sooner than I thought!

Noticed going through my checklist launching on Memorial Day. She still drove fine but now I have an excuse!

4 or 5 blade? pitch for 5.0 GL?

Love to hear all suggestions.
Liquid, I've had good luck with Prop MD in Eden Prairie, MN, but I know there are many other places that do good work fixing dinged up props as well. They welded some metal on and reshaped my stainless steel Volvo duo props looking like new for about $200, instead of buying a new pair for $1200-1600.
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Re: Propeller selection info and speeds

Post by Big Block Power »

I wish I knew Volvo props better. I loved the high five. Small prop held the water great, great hole shot and could spin some rpms with it. I don't know if you could spin a rev 4 those are crazy good props all around. I am sure you can buy a new aluminum or a great shape used one for right around a$100 so not sure I would waste my time fixing that one. I bought common props I knew I could resell if I didn't like it. That's how I found the ones I looked. 19-21 pitch it's a easy resell so just have to find one at a good price. I used eBay and cl mostly
I just posted my f8 dp on eBay for $500 so I could move up to Hill Marine 4 blades.
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