Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Prop selection for 1993 Dauntless 15
Posted by Jubilee332 on 02/24/13 - 11:40 AM
#1
Info needed on my 1993 Dauntless 15 with Yamaha 70 2stroke
Current rig has Yamaha K19 prop (13x19)
Engine ht. is level with bottom (will be raising engine to highest setting just to get data)
What should i expect RPM and top speed to be with this setup.
From what can see i would think this boat will need stern lift due to the deep vee of the hull. (Yes or No)
I want to replace propeller and i'm looking for recommendations for a Stainless Steel. Keep in mind that i want to run at the higher height on the transom.
3 Blade model #
4 Blade model#
Posted by Tom W Clark on 02/24/13 - 12:08 PM
#2
The two stroke Yamaha 70 has a 2.33:1 gear ratio and a 5000-6000 RPM recommended WOT engine speed range.
If we think your boat is good for speeds up to 40 MPH then I recommend the 14" x 15" Stiletto Star 4.25.
If your boat is capable of speeds in excess of 40 MPH then the Star will not work because 15" is the highest pitch they offer.
Posted by Jubilee332 on 02/24/13 - 12:51 PM
#3
Thank you Tom for the info but i thought the Star II also came 14 x 17. I will also be looking at the Turbo Quest 3 blade 13.125 x 18 and the Quest 4 blade 13.125 x 17 with the motor raised all the way up on transom. Do you agree that this hull needs stern lift vs. bow lift.
Posted by Tom W Clark on 02/24/13 - 1:10 PM
#5
Star II is the old model name and implies the old press-is rubber hub. Since 2008 the intermediate size Star is known as Star 4.25 and uses a universal square-bore hub kit.
There is no 14" x 17" Star, new or old.
I have no personal experience with the Quest models. I would love somebody to try one and offer some feedback. I think they might be a good fit for your application.
What pitch you select would depend on how hast your boat goes. Have you measured it top speed with a GPS and the propeller you have now?
Posted by Jubilee332 on 02/24/13 - 1:34 PM
#6
Tom, At this time I have no data as I just purchased this boat but will be trying the Quest propellers. I believe that I can get to 47 to 50 with a slight chop to keep the boat loose. With the 4 blade I probably will have to raise motor higher than what I currently can go. When i get more info I will post all my data. Can't wait to get started!!
Posted by Finnegan on 02/24/13 - 1:53 PM
#7
I would be surprised to see the Dauntless do more than 36 -40 MPH with the Yamaha 70. Tom's prop recommendation should be considered.
To get into the 40's, I think you would need a bigger cube 75 like a Merc 2-stroke 75 or Evinrude E-tec 75. Maybe the new Yamaha F70 would do it also.
Posted by Tom W Clark on 02/24/13 - 2:13 PM
#8
47-50 is not realistic.
The factory test data I have for the Dauntless 15 shows it doing 41 MPH at 6100 RPM with two aboard a test boat with the Yamaha 70 TLR and a 13-1/4" x 17" stainless steel propeller, though it does not say what model of propeller it was.
I would speculate that with the engine raised and just one person onboard it might be capable of 42-43 MPH.
[Aside: the test sheet shows the Dauntless 15 doing 43 MPH with the Johnson 70, singe person aboard and a 21" pitch prop with this note: "motor all the way up"
Two tests were done with the Mercury 75, 42.5 MPH with the 20" Laser II and 44.7 MPH with the 22" Laser II That's pretty good!]
Posted by Jubilee332 on 02/24/13 - 2:41 PM
#9
I will post data when I get results but with the Yamaha 2 stroke I might have to modify it some to get it to swing a slight more pitch to get to 50. They are tuned for low to mid range power so I know I can get to 45 with the correct prop and engine ht.
Posted by Tom W Clark on 02/24/13 - 3:28 PM
#10
If top speed is what you are after, then you should choose the Yamaha Performance Series 3-Blade/Turbo 1/Stiletto Advantage model.