Whaler Central - Boston Whaler Boat Information and Photos

Posted by trionfale on 04/10/23 - 9:51 AM

I would like to re-power Maripà 2 (http://www.whalercentral.com/infusions/personal_page/ppages.php?ppage_id=22):

1989 Outrage 18'
T-H Marine 25” bracket
12" x 14" homemade trim tabs
2011 Evinrude ETEC G1 E150DCX 433 lbs
45 mph 5,500 rpm WOT
VIPER 14 3/4 x 19”

I’m going for a new YAMAHA F115 four-stroke 377lb
Comes with a 13.25 x 17" Painted Stainless Steel (K) propeller.
I'm afraid it won't go at all.
I look forward to hearing some of your advice.

Edited by trionfale on 04/10/23 - 9:52 AM

Posted by Phil T on 04/10/23 - 10:06 AM

P -

The engine does not include a prop, the dealer is selecting that prop as a guess.

There is some good performance data on the Outrage 18 and the F115:

Prop installed 13 1/4 x 19 Yamaha Painted Stainless Steel
Engine mounted all the way down.

Test results with a Yamaha 115 hp four stroke EFI on a 1988 Outrage 18, no bottom paint, motor mounted all the way down:
(Wind variable 5 kts; smooth fresh water lake; air temp 65 degrees; water temp approx 60 degrees; approx 1000 ft altitude; humidity approx 65%; on board me (210 lbs) & brother-in-law Larry (170 lbs); no RPS--it's at home all torn apart being spruced up; no live bait tank any more; 30 lbs of weights midships; two batteries in console; anchor chain & rode; 3/5 tank of gas, maybe 37-8 gallons.)

All measurements via GPS and Yamaha digital multi-function tach. No current and negligible wind, so I didn't run in reciprocal directions.

700 rpm = idle
700 rpm = 3.1-3.3 mph
1100 = 4.7
1500 = 6.2
1600 = 6.3
2200 = 8.0
2500 = 9.0
2800 = 11.4
3100 = 16.2 (barely on plane, trimmed all the way down)
3500 = 22.0
3700 = 24.6
4500 = 30.0
4600 = 31.7
4800 = 34
5000 = 36.0
5700 = 40.8-41.1

Edited by Phil T on 04/10/23 - 10:10 AM

Posted by trionfale on 04/11/23 - 11:56 PM

Dear Phil,
many thanks for your prompt and comprehensive reply.
Your evidence is extremely important to me.
3100 rpm = 16.2 mph (14 Knots) -barely on plane- is a crucial information.
I'm not going to remove my T-H Marine 25” bracket and the two large trim tabs because I'm convinced that they largely contribute to facilitate to stay on plane.
I mainly sail the Mediterranean Sea that can be surprisingly choppy.
I will take the 13 1/4 x 19 prop as a reference.
Paolo

Edited by trionfale on 04/11/23 - 11:57 PM

Posted by Phil T on 04/12/23 - 9:18 AM

Caio Paolo -

With the reduced power, you many want to experiment with a 4 bladed prop.

This will help get up on a plane at a lower speed and keep the hull from falling off plane.

When going from 3 to 4 blade, you drop 2 inches of pitch.

Hope this helps.