I am trying to find the right prop for my 2520 dvsc. I currently have the stock 17 inch on a 250hp ox-66. I am getting 25mph at 4100 rpm. wot is 34mph at 5100 rpm. This seems low for wot. The prop calculator says I have way too much slip. My dealer tells me i dont want a four blade because it would bite too much and put too much stress on the engine because of boat weight. What do you guys that have the same set up run? What are your numbers?
prop problems....
- Thread starter green74
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Fishinfireman
Well-known member
I have the same boat with a 250 2 stroke on a notch. My boat is usually heavily loaded with 7 people, 300# of ice and all the gear. I have settled on the Enertia 16 with the flo-torq IV hub. I am happy with the performance and the Flo-torq IV hub eliminated the low speed prop chatter I had with the other props.
If you are only getting 5100 rpm, then you are over-propped and need to drop in pitch. Rule of thumb is 300 rpm per inch of pitch. I would drop at least 2".
The guidance that a 4 blade prop would provide too much bite and be hard on the transom sounds bogus to me. The back of those Parkers are made to hold twins, and depending on the model, you can find a pair of F-250s hanging there. That is a lot of weight and HP, and Parker wouldn't rig them that way if they didn't think the transom and brackets would hold it.
The "stress" is on the motor because it is over-working. It is over-working now with the 3-blade prop, regardless of what prop you may consider going to. Trick is to drop the pitch so the RPM comes up to somewhere between 5,700 and 6,000 rpm.
A 4-blade prop of less pitch should give you less slippage, and more rpm. If you can get someone to let you test a prop, you might want to try a 4-bladed prop of 2"-3" less pitch than you have now.
The guidance that a 4 blade prop would provide too much bite and be hard on the transom sounds bogus to me. The back of those Parkers are made to hold twins, and depending on the model, you can find a pair of F-250s hanging there. That is a lot of weight and HP, and Parker wouldn't rig them that way if they didn't think the transom and brackets would hold it.
The "stress" is on the motor because it is over-working. It is over-working now with the 3-blade prop, regardless of what prop you may consider going to. Trick is to drop the pitch so the RPM comes up to somewhere between 5,700 and 6,000 rpm.
A 4-blade prop of less pitch should give you less slippage, and more rpm. If you can get someone to let you test a prop, you might want to try a 4-bladed prop of 2"-3" less pitch than you have now.
captbone
Well-known member
You current prop is too big.
In my opinion, the perfect prop for you will be
a 15pitch Mirage Plus( I got a used one for $125 plus shipping)
or
a 16 Pitch Enertia (like recommended above).
The Enertia will be pricy but will performance just slightly better. I would bet that these props are the ticket. You could also try a 15pitch Rev 4 if you wanted to try a 4 blader.
Just my 2 cents.
In my opinion, the perfect prop for you will be
a 15pitch Mirage Plus( I got a used one for $125 plus shipping)
or
a 16 Pitch Enertia (like recommended above).
The Enertia will be pricy but will performance just slightly better. I would bet that these props are the ticket. You could also try a 15pitch Rev 4 if you wanted to try a 4 blader.
Just my 2 cents.
Outta Here
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There's three responces and, IMO all three are very good info. The only wrong info posted here is the "dealer's advice".
Not to steal the thread, but why is it so hard to get good info from the "professionals"?
Maybe they should be reading CP?
Not to steal the thread, but why is it so hard to get good info from the "professionals"?
Maybe they should be reading CP?
PaulH / Emily S
Well-known member
That 5100 RPM / 34 MPH is common. All the 2520DVSC I've been on (with single 250 two strokes) were rigged that way, including my own.
Interesting I've repowered mine with an F250 this year. We played with lots of props, bear in mind that the four stroke wants to max at higher (6000 RPM ideal) and has a differant gear ratio.
The guys who repowered my boat have alot of experience, in their mind, on a marginally powered boat (lets face it 250 is marginal for this rig) you want to maiximize the diameter first, than adjust pitch to get propper RPM at WOT.
What we ended up with is a 15.75" x 15 Yamaha SWSII. The motor turns 6000-61000 WOT whci is ideal. The top speed is the same as the old motor, about 32 knots, light load.
The new setup performs better than old in many ways besides the obvious (economy baby !!). That bigger prop holds the boat on plane better, giving me a wider range of cruise RPM.
So, if I were to monkey around with a new prop on that rig, I would spin the largest diam that you can, than, adjust the pitch for suitable RPM.
Bear in mind though, thousands of 2520DVSC are rigged with the prop you are talking about, I'm pretty sure Parker woudl have switched props if it made sense.
Let us know how you make out.
Interesting I've repowered mine with an F250 this year. We played with lots of props, bear in mind that the four stroke wants to max at higher (6000 RPM ideal) and has a differant gear ratio.
The guys who repowered my boat have alot of experience, in their mind, on a marginally powered boat (lets face it 250 is marginal for this rig) you want to maiximize the diameter first, than adjust pitch to get propper RPM at WOT.
What we ended up with is a 15.75" x 15 Yamaha SWSII. The motor turns 6000-61000 WOT whci is ideal. The top speed is the same as the old motor, about 32 knots, light load.
The new setup performs better than old in many ways besides the obvious (economy baby !!). That bigger prop holds the boat on plane better, giving me a wider range of cruise RPM.
So, if I were to monkey around with a new prop on that rig, I would spin the largest diam that you can, than, adjust the pitch for suitable RPM.
Bear in mind though, thousands of 2520DVSC are rigged with the prop you are talking about, I'm pretty sure Parker woudl have switched props if it made sense.
Let us know how you make out.
B-Faithful
Well-known member
It is expensive to test but I ended up with an Enertia. the Thinner blades and smaller diameter allow me to get the load down on the motor. Despite the 14.5 diameter on my 17 pitch, I think the blade surface is greater than that of the Mirage plus. I think a 16 Pitch x 14.82" diameter (diameter is greater the when you go down in pitch) would work great on your boat.
http://cgi.ebay.com/ebaymotors/MERCURY- ... enameZWD1V
Do a search online of the new enertia prop made of x7 alloy
http://cgi.ebay.com/ebaymotors/MERCURY- ... enameZWD1V
Do a search online of the new enertia prop made of x7 alloy
