Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: 1988 17' Montauk 70HP 4 Stroke--Best Prop?
Posted by tobyport on 11/26/12 - 10:55 AM
#1
Which propeller should I use? I'm in the process of re-powering a 1988 17' Montauk with a Yamaha F70 4 stroke. I purchased the boat with a F90 4 stroke, but I wasn't pleased with the way the boat managed the heavier engine. Plus, I don't need to run 45 mph in a 17' Montauk. Yamaha performance bulletin for the F70 suggest a 13 1/2 X 14 prop, but the local Yamaha dealer says they use a 13 1/4 X 14. Would there be much difference in the two props? Which one should I choose for all around performance, not for max speed?
Edited by tobyport on 11/26/12 - 10:57 AM
Posted by Phil T on 11/26/12 - 11:12 AM
#2
Yes there is a difference.
Tom Clark's friend with a 2002 Montauk and a new F70 on it. He reports 38 MPH @ 6200 RPM using the 13-1/4" x 14" Yamaha Performance Series three blade propeller.
Make sure the motor is mounted at least "2 holes up". The top bolts should go through the 3rd set of holes when counting down from the top.
Top Set of holes
O
O
O <----bolt through this hole
O
O
Edited by Phil T on 11/26/12 - 11:13 AM
Posted by tobyport on 11/26/12 - 11:13 AM
#3
Many thanks for the information!
Posted by DennisVollrath on 11/26/12 - 1:37 PM
#4
Hi Tobyport,
I have a 1988 Montauk with a 2011 Yamaha F70LA. I have it propped with a Stiletto Advantage I, 13.25" x 13". It is probably somewhat under-propped. My top speed is about 36mph @ 6300rpm, rev limited by the motor. The 15" version of this propeller was too much and the boat felt sluggish. With the 13", I get very zippy hole shot. Best economy is around 4000rpm, with about 7.5-8 mpg.
I think Tom Clark has suggested that the Yamaha 13.25" x 14" prop you mention may be ideal for this boat/motor combination, but I have not yet had the opportunity to try it. I am pretty satisfied with the setup I have at this point.
This motor only has 4 mounting holes (not 5), and I have it mounted all of the way up.
In addition to the lighter motor, I also moved the battery to the console. The combination makes a nice difference in weight distribution. The bottom paint at the stern is now exposed by 2-3".
Dennis
Posted by tobyport on 11/26/12 - 1:56 PM
#5
Dennis--Thank you for the information. i read elsewhere that your Stiletto is comparable to the Yamaha SS Performance 13.25 X 14. I'm looking forward to running the Montauk with the F70. The F90 was too much engine. Previous owner had replaced his original 2 stroke Yamaha with the F90 and no hydraulic steering. It was a beast to operate. Sad thing is that he probably could have put the F70 and hydraulic steering on the boat for less than what the F90 cost. The only good thing his shop did during the swap was to move the battery to the center console. At any rate, I've got a F90 with only 23 hours that I need to sell!
Posted by Joe Kriz on 11/26/12 - 2:15 PM
#6
You haven't told us where your engine is mounted.
Please let us know so we can continue.
Posted by tobyport on 11/26/12 - 4:20 PM
#7
Joe Kriz wrote:
You haven't told us where your engine is mounted.
Please let us know so we can continue.
Joe--Will do once the boat is out of the shop. Pictures and info forthcoming...
Posted by Slickityd16t on 11/26/12 - 9:39 PM
#8
PM Petrus I know he was looking for an engine for his Montauk only thing is he's in Sweden
tobyport wrote:
Dennis--Thank you for the information. i read elsewhere that your Stiletto is comparable to the Yamaha SS Performance 13.25 X 14. I'm looking forward to running the Montauk with the F70. The F90 was too much engine. Previous owner had replaced his original 2 stroke Yamaha with the F90 and no hydraulic steering. It was a beast to operate. Sad thing is that he probably could have put the F70 and hydraulic steering on the boat for less than what the F90 cost. The only good thing his shop did during the swap was to move the battery to the center console. At any rate, I've got a F90 with only 23 hours that I need to sell!
Posted by Petrus on 11/27/12 - 12:54 AM
#9
Hi,
I've ordered a new Suzuki DF90 today (I traded my Yamaha F50 for a very good price)
I'm surpriced though, that you didn't like the Df90. I tried a montauk 17 with a DF115 2001, and it was no problem to handle.
I was close to by a used Yamah F70 2011 but thoght I would regret that later.
Posted by tobyport on 12/07/12 - 5:50 PM
#10
Finally, my re-powered 1988 Montauk 17' is back in the water and it really looks and feels like a new boat, though I'm still in the break-in period. Removed a Yamaha F90 and replaced it with the F70. Losing 110 lbs. on the transom made a big difference in the way the boat handles and the way it sits on the water. Personally, I thought the F90 was too large, aesthetically speaking. Haven't got it on a plane yet, much less WOT, but pleased with "feel" thus far. Will update as the hours progress. Yamaha SS Performance 3 Blade Prop Propeller 13 1/4 X 14.
http://s720.beta.photobucket.com/user...lerMontauk
Edited by Joe Kriz on 12/07/12 - 9:35 PM
Posted by Joe Kriz on 12/07/12 - 6:28 PM
#11
It is best to put ONE link to your entire album rather then several links that people have to keep clicking on to view them.
Posted by NJjohnmontauk17 on 12/10/12 - 5:30 PM
#13
nice clean installation. nice boat
Posted by Joe Kriz on 12/10/12 - 5:36 PM
#14
toby,
You still haven't told us which holes the motor was mounted in.
Can't tell from the photos.
Can make a big difference.
Edited by Joe Kriz on 12/10/12 - 5:38 PM
Posted by tobyport on 12/12/12 - 2:37 PM
#15
I added a photo showing exactly where the engine is mounted. Almost through the break-in period and ready to put her on a plane...
Posted by wing15601 on 12/12/12 - 3:15 PM
#17
John, I have owned many outboard powered boats over the years but have never seen the use of two nuts tightened together as on your motor bracket installation. I think all of mine were either nuts with lock washers or locknuts with the nylon insert and lock washers. They did use lock washer with those nuts and bolts didn't they?