Hello Everyone, Can any of you...

[Scoobie]

Hello Everyone,

Can any of you Sundancer 260 owners tell me how many miles per hour you getting out of your boat motors? I have a 2008 with a 6.2L and am only getting just under 30mph out of the thing at 4600 rpm. I know its a heavy boat but would think it should be near 40mph....thanks

[Bow_Tie]

If you are hitting rated RPM's and doing 30 mph, you're "all in". If you increase the pitch you will not hit rated RPM' and will be harming your engine and f you decrease the prop pitch, you'll loose mph and increase RPM's, not good. You'll need to buy a boat with twin engines to hit 40 mph.

[Scoobie]

Thanks Bow Tie, the max WOT rpm is 4800 to 5200. The boat is only going to 4600. The prop is the orginal OEM. So, I"m thinking I might not be reaching my full rpms

[Scoobie]

I should have stated the max WOT is from the engine spec sticker.

[wingless]

The bottom condition also affects speed. The bottom must be clean, clean, clean to attain maximum velocity.

The onboard mass can affect velocity.

The amount of tools, fuel, water, waste and passengers contributes to the variable mass. Try w/ an empty waste tank, very low water tank, not full fuel tank and two people to determine maximum velocity.

[Bow_Tie]

Gotcha! If you can reduce pitch you'll get more RPM's. If 4800-5200 is WOT, change the pitch 2" and see how the boat performs. A rule of thumb is 1"= 100 RPM's. Sometimes it's a trial and error when trying to find the best props. Also, I've found that boats gain weight over the years? Lol, I guess I've accumulated too much stuff on board! I'd bring all the information to a professional prop guy and start there. I know when I reduced pitch on my props (28 x35) to 28x33, my engines where "happier" but I lost 1 MPH but gained 1-2 GPH. I have a totally different boat, but in theory, prop calculations are the same. A 35" pitch will travel 35" on one complete revolution. If the boat is too heavy, more load, more load= slower boat and more fuel used. Are your props original? If not, find out from SR what the original props were and the advertised speed. Keep in mind that manufactures always overprop the boats in order to get maximum speed, but if you can't get rated RPM out of the engine something is wrong and should be corrected, even if you can't get 40 MPH, you need to get to rated RPM at WOT. Good luck.

[Bow_Tie]

Wingless is absolutely correct, the bottom should be clean, I assumed you trailered you boat. If you're in a slip clean the bottom first, and lighten up the load. Maybe your boat gained some weight?

[Scoobie]

Thanks Wingless and Bow Tie, I'll need to get the suggested mph for that boat from a dealer...just bought it so I'm not sure how it ran new. During the test drive, I was only able to get up to 25mph with 3 people and a half tank of gas....seems a little low. Bottom wasn't that dirty.

[Scoobie]

Here's the motor specs from the sticker

[wingless]

The prop pitch may be okay.

Start w/ the bottom clean, instead of not "that dirty" to determine WOT.

Other things that can affect performance is timing, fuel injector condition, spark arrestor condition, fuel pressure regulator operation, intake plenum and sensor condition and throttle body adjustment. (All normal engine tuning stuff)

[Scoobie]

Thank you for the info Wingless

[Brite_Idea]

You need a different set of props. Since you have established your current WOT I suggest that you call Hill Marine out in Cali. When you give them your info they will suggest the correct props. I;m having the same problem on a heavier boat and as per his suggestion I'll be going down in pitch but changing to 4 x 4 props.

[Cape_man]

I had my 260 with 6.2 mpi out yesterday, calm day and got it to 44 mph. I’ve only had it for one year now so I can’t tell you yet what pitch my props are . I can read the.numbers if it helps.

[Cape_man]

I forgot to mention it’s a 2003.

[Scoobie]

Thanks Brite Idea, but I believe there's something wrong with the boat. The props are the orginal that came with the boat.

[Scoobie]

Hi Cape Man, I really appreciate the info you gave. This is exactly what I needed. My 260 should be getting better speed and rpms; I just bought the boat. If you could get me your prop numbers and RPMs at the max mph you're running, that would help.

[Scoobie]

The prop numbers will list the pitch

[d9ever]

2000 340 Dancer with 2 7.4--I run them at 3500rpm and get 27mph. I don't like beating them up at red line (4,400rpm)

[Scoobie]

Hi d9ever, thanks for sharing. I'm looking to see what mph the max WOT is for Sundancer 260. I agree with you that we don't want to run our boats a the max speed, they are cruisers. But I'm trying to get a better idea of the performance of the 260. I"m not reaching my WOT rpms which is' between 4800 to 5200. I"m only getting 4600 rpms with a speed of ~25 mph. Boat only has a half tank of fuel and 3 people in it. The engine hours are 160 which is pretty low. Props are OEM originals

[Brite_Idea]

The important WOT numbers are there to make sure you're running at the best load at any speed. It doesn't hurt an engine to reach max recommended WOT. I'm not saying run at full throttle all day just be able to reach the recommended WOT to ensure the boat is propped correctly.

[Scoobie]

Hi Brite Idea, I agree, just need to make sure that I'm able to reach the WOT to ensure boat is performing correct.

[Cape_man]

I apologize for the delay , just got back out today.
So here it is-
Prop #s
48-823661 L- 20P
Mercury Marine
48-823662L - 20P
Stainless steel
WOT - ( today) 42 MPH @ 5,200 rpm
Also - 31 MPH @ 4,200 rpm
and 23 MPH @ 3,500 rpm

[Brite_Idea]

I know the 6.2 WOT is 5200 rpm but you'd probably get better mid range performance with four blades on the forward prop. Thanks for posting your results.

[Scoobie]

Hi Cape man, both props are OEM Mercury,

Their prop #'s are same as yours:
48-823661 20P
48-823662 20P

I will be taking it out to the river this Saturday; gonna put some higher octane gas and mercury fuel additive in it.
Will get back to you with some rpm & mph numbers.

Can you tell me again if your boat is a Sundacer or a differnt model? Mine is, and it weighs ~7900lbs according to NADA...I think that is a little high though.

[Scoobie]

To me, your boat is running optimal!

[Paulswagelock]

Is the bottom fouled with algae etc?

[Scoobie]

Hey Everyone, just wanted to get back to you on my speed. Before taking it out, I filled the tank half full with premium gas. I then added some Mercury Quickleen fuel system cleaner. I also scrapped any barnicals off the bottome ( there wasn't that much). When I test drove the boat, I was able to reach 34mph @ 4600 rpms, at 75% throttle. So, I'm thinking everything is good. One thing I did learn is the boat leans quite easily. I'll definitely need to learn how to use the trim tabs...thanks for your help.

[Brite_Idea]

One question, what is your max RPM's?

[Scoobie]

I couldn't get there due to the lean I was experiencing after reaching plane; first time really driving the boat and I need to learn how to use those trim tabs. Also, had 4 people and 1/2 tank of fuel.
The 260 is top heavy and the arch catches the wind quite a bit.... anyone driving this boat will need to use trim tabs.

[Special_Ed]

I have a 1998 250. Once on plane small adjustments to the motor trim will produce another 3-4 mph.