1996 21 JUSTICE F300

Optimizing the performance of Boston Whaler boats
conch
Posts: 172
Joined: Sat Oct 17, 2015 8:43 am
Location: Florida Keys,Hawaii,Mississippi

1996 21 JUSTICE F300

Postby conch » Sat Sep 07, 2019 9:34 am

On my 21 JUSTICE with Yamaha F300 I am going to try a Yamaha SWS II 19-pitch propeller soon. I have a borrowed Mercury Laser 19 now just to bring the boat home, and performance was poor all around.

I did not try much of anything, just running home from the ramp.

Seven on board and 50 gallons fuel. Boat speed was 42-MPH and engine accelerated to 5,600-RPM. The PVS vent plugs were out and trim was medium.

Some suggest the Mercury Enertia 15, Yamaha SWS II 17, or a Mercury REVOLUTION4 17.

Boston Whaler states bare hull 21 Outrage weighs 2750-lbs.

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Phil T
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Location: Was Maine. Temporarily Kentucky

Re: 1996 21 JUSTICE F300

Postby Phil T » Sat Sep 07, 2019 11:29 am

I don't have any prop suggestions on my owner recommended sheet so I am interested in your evaluation process.
1992 Outrage 17
2019 E-TEC 90
2018 LoadRite 18280096VT
Member since 2003

NLA01
Posts: 170
Joined: Sat Nov 14, 2015 10:25 pm

Re: 1996 21 JUSTICE F300

Postby NLA01 » Sat Sep 07, 2019 7:45 pm

Before you jump to 15 and 17 you may want to try a different 19 because I think that Laser prop is a bass boat prop with high rake and cup made for light hulls. It also may not be a good diameter for your hull weight and design. Try a MIRAGEplus 19 or ENERTIA 19.

Seven on board is a lot of people; what was the combined weight?

Archie

conch
Posts: 172
Joined: Sat Oct 17, 2015 8:43 am
Location: Florida Keys,Hawaii,Mississippi

Re: 1996 21 JUSTICE F300

Postby conch » Sun Sep 08, 2019 8:14 am

Hi Archie. [Total crew weight associated with the anecdotal performance data reported above was] probably about 850-lbs. There were two were small children and five adults aboard. There was no gear on board other than safety gear.

We just grabbed the LASER 19-pitch propeller on the way to launch when I realized I forgot to mount a propeller.

The [acceleration from a standing start to being on plane] was terrible, but this [propeller was installed] just to get the boat to the house. The boat elevator people were coming in the morning and needed the boat for a final fitting to set the lift bunks and auto limit up-down switches.

The Yamaha SWS II 19-pitch should be here next week.
Chuck

21 Boston Whaler stern 4.jpg
Fig. 4. Stern view
21 Boston Whaler stern 4.jpg (49.25 KiB) Viewed 9444 times

rtk
Posts: 122
Joined: Fri Oct 16, 2015 7:06 am

Re: 1996 21 JUSTICE F300

Postby rtk » Sun Sep 08, 2019 10:34 am

I had a 1997 21 Outrage with a 2003 Mercury 250 horsepower EFI engine. It was a well loaded boat including hard top t-top. My top speeds were in the range of 46-50 miles per hour depending on temperature and fuel load. The propellers I tested were 17 and 19 pitch Mercury Mirage, Vensura (Offshore) and REV4. Maximum rpms for the engine were 5,750. I believe the gear ratio was 1.75 to 1.

The 17 pitch was not adequate- ventilation/cavitation was a major problem. 19 pitch was the propeller size that worked best to keep the wide open throttle operating range at 5400 to 5750 rpms. The Vensura was a great all around propeller but a bit slow on the top end. The REV4 was the fastest but ride quality was not as good as Vensura. The Mirage worked well- that prop was in the middle of my preference but I experienced the best fuel economy with the Mirage.

I understand that the Justice version of this hull is heavier (250 pounds) but I would think with an engine that has 50 more horsepower should be able to turn a 19 pitch propeller and easily reach a top speed of 50 mph. That 300 Yamaha performs very well so I do not believe that it is a weak engine by any means.

I have a 19 pitch Vensura that you are more than welcome to test. I can send it to you tomorrow. You would just need the hub kit for your Yamaha. If you like it I'll sell it to you cheap if not just ship it back.

What a great boat you found- I love this hull and it was a pleasure to own one for 11 years. It is a beast of a 21 foot boat I really think you'll enjoy it.

Rich

conch
Posts: 172
Joined: Sat Oct 17, 2015 8:43 am
Location: Florida Keys,Hawaii,Mississippi

Re: 1996 21 JUSTICE F300

Postby conch » Sun Sep 08, 2019 12:10 pm

Thank you very much for the offer Rich and I will let you know. I do have hub kits for the Yamaha, both Flo-Torq II and Solas/Rubex #203.

Was your T-top cloth material or fiberglass? I have never watched the cutting and installation of mounts (antenna,radar,lights,etc.) thru the cloth.
Some articles said to burn the edges to melt and seal the cut. I will search for a video or some first hand info. I need to try to confirm what the cloth is made of and will it melt.
Chuck

rtk
Posts: 122
Joined: Fri Oct 16, 2015 7:06 am

Re: 1996 21 JUSTICE F300

Postby rtk » Mon Sep 09, 2019 8:52 am

You're welcome Chuck.

The t-top was a fiberglass hardtop.

I have one of these that I use for cutting Sunbrella canvas cloth. The cutter does melt the cloth but only on the edge. If you simply cut the cloth with a knife or scissor the cloth will likely unravel and fray.

https://www.sailrite.com/Sailrite-Edge- ... e-110-Volt

For installations on a cloth t-top in the past I have just cut the cloth to form the individual bolt holes and mounted the accessory on top of the Sunbrella cloth. Put a bit of sealant or adhesive between the cloth and the accessory and you should be good to go with no exposed ends of the cut cloth and no fraying of the cloth.

Rich