Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Engine config and fuel consuption

Posted by Gonorn on 07/05/17 - 8:03 AM
#1

HI all

I'm after a little advice or guidance.
I have been given a 17ft outrage II 1996 model with a mercury 115 2 stroke. I have never owned an BW or anything with an engine of this size. Having spent many hours searching for answers to simple questions ive been left with a few blanks and I wonder if anyone can help me fill them in.

First off the fuel consumption is pretty bad, I did a short trip at low speeds due to 10knt speed limit in the harbour then ventured out into the bay. A round trip of roughly 18 miles. I'm not a speed demon so never once maxed it out to see what it she can do as there is no tach fitted so I cant get a true RPM reading. I fished for a couple of hours with 3 of us on-board. we used 45l of fuel, my first question is, is this a lot or am I just used to smaller engines that burn less?

Now a lot of this trip was in the no wake zone and thus I had to keep under the 10 knots roughly (10 miles of the total distance) She would not plane at much under 12-13 knots so I'm wondering if its mainly down to this.

After reading much here I am also wondering if the engine is mounted to low and is dragging? pic on my page.

[url]http://www.whalercentral.com/infusions/personal_page/view_personal_page.php?user_id=40582
[/url]Also the previous owner mainly used her for water skiing and was loaded so cost of running was never an issues, where as I want to use here for fishing so top speed is not so important and sensible running costs are more important. She pops up on the plan real quick so I'm wondering if maybe she is propped more for water sports and less economy.
The engine is

Mercury 115 2 stroke
Model number 115EXLPT 1996
Max rpm 5250
gear ratio 2.07 to 1 (I think)

If you need any more info let me know and ill see what I can find. Any help and guidance is greatly received.

Edited by Gonorn on 07/05/17 - 8:07 AM

Posted by DennisVollrath on 07/05/17 - 10:32 AM
#2

Hi,
That speed you were traveling at just under planing is the worst for fuel efficiency. Most of the hull is still wet and you are ploughing & pushing lots of water out of the way. My fuel efficiency drops to less than half of my best cruise at that speed,

Sounds like you may have averaged roughly 1.5mpg going at that speed. A carbuereted 2 stroke 150 I used to own got around 2.9 mpg at cruise on a 1985 Outrage 18. I guess I don't find your result all that surprising, which is not to say you wouldn't benefit from motor height adjustment and/or re-proping.

Have you been in a position to measure consumption while on plane at a cruise? That would give you a better sense of potential economy.

Dennis

Posted by Gonorn on 07/05/17 - 12:27 PM
#3

HI Dennis

Thanks for the reply, I've only Just finished installing a new fish finder/gps unit a striker 5cv. I'm hoping for some nice weather this weekend so I can run her up in the ski zone, now I have the gps unit installed I can get some accurate distance and speed calcs in.
Ill run up an external tank with fuel in and then do some runs, this should get me a better idea of cruising performance. my brother used it last year once and he said it drank fuel then but I figured there are so many reasons for this I did not pay to much attention.

I've been trying to find a taco for it so I can see what rpms she is at on WOT, I have a small digital tiny tac being delivered so this should give me more info.

I have even toyed with fitting a kicker as a newer 4 stroke kicker should be cheap to run in the no wake zone at around 6 knots as its such a large part of my trip each time I go out.

Thanks

Mike

Edited by Gonorn on 07/05/17 - 12:28 PM

Posted by Joe Kriz on 07/05/17 - 12:34 PM
#4

Where is your motor height now?
http://www.whalercentral.com/articles...cle_id=106


Posted by Phil T on 07/05/17 - 1:05 PM
#5

One way of measuring WOT speed without a GPS is have a partner boat run next to you.

You do want to install a real tach to test the prop you have and also know where the "sweet spot" is for cruising at the best rpm/gph spot.

Where in England is the boat run ?

Posted by Gonorn on 07/06/17 - 8:56 AM
#6

HI Again all


In answer to some of your questions and a bit more info.

I have now installed the gps so I will do some speed runs over this weekend so I will be able to see how fast a WOT.

The engine is mounted one hole up as per the diagram.

I have added a few more pics to try and show where the engine sits where its mounted.

I also tried to see what the specs on the current prop are but as you can see by the photo its pretty warn out, I'm going to try and take a pencil and paper down and see if I can get a rubbing.

And I live in Poole Dorset on the south of the Uk which is where she will be fishing. We have the 2nd largest natural harbour in the world so it would be rude to not have a nice BW running to enjoy it. Due to where I live the weather will need to be pretty bad for us not to be able to get out and fish all year around, and once we get to October there are no speed limits!

Thanks for your time all.

Mike

Posted by Phil T on 07/06/17 - 10:00 AM
#7

Mike -

Poole is fabulous. Lucky you !!

Let us know what you find out. Once we know your wide-open-throttle speed and rpm's we can advise on optimum mounting height and prop.

With any 2 stroke, no-wake speeds burn lots of fuel.

Posted by EJO on 07/06/17 - 10:25 AM
#8

Mike first I have to say; "You lucky dog that is a great boat to be given". I visited the Royal Motor Yacht Club there once a long time ago in a sailboat after having sailed from Den Helder and around the Ilse of Wright before crossing the Channel back to the French coast (Dieppe) and back North East to Den Helder, what a marvelous two weeks that was.

You keep saying "No Wake" zone but also at the 10 knts speed you are talking about she'll make a pretty good wake being just short of getting onto plane.
Is it a no wake zone or a speed limit zone.
No matter what it is of these two you are probably better of just idling and taking more time.
If you can get a small kicker that would be great.
Bottom line inherently a carburated 2 stroke of that power will be a gas guzzler.

Posted by Gonorn on 07/06/17 - 12:10 PM
#9

Thanks for the feed back all.

Aye I know I'm pretty lucky with the boat and where I live!

Its a 10 knot speed limit all the way, but I pass though swinging moorings where the no wake comes in as well, which has tenders and people on there boats enjoying the day.

Like you said she makes more wake off the plan chugging along, so I tend to almost idle along at low speed 5/6 knots which is why I am thinking about a kicker as I'm limited to speed and wake. I figured a slightly more modern 4 stroke kicker might be much more fuel efficient at low speeds and it gives me a bit piece of mind with the back up. And remember in the uk fuel is priced at £1.10 L atm which works out roughly $5.00 per us gallon (I think)

Thanks again

Mike

Posted by EJO on 07/06/17 - 12:40 PM
#10

Mike
I know of the prices for gasoline per liter as a Dutch citizen

A small 4 stroke kicker won't use a liter doing that. Good luck in finding one and happy boating.

Posted by Phil T on 07/06/17 - 1:05 PM
#11

While the closed off transom of the Outrage 17 I and II is not easy for installing a kicker, there are three members who have done it and we can see their installs.

Royboy did one his previous boat shown here:
http://www.whalercentral.com/infusion...er_id=4320

Petemax did an interesting install using his swim platform:
http://www.whalercentral.com/infusion...er_id=4634

Sweet Tooth went with a Tanner stand off bracket. Great photos to show his project.
http://www.whalercentral.com/infusion...r_id=13606

Product page: http://www.tannermfg.com/motorbracketsorbrackets

Edited by Phil T on 07/06/17 - 1:07 PM

Posted by Gonorn on 07/16/17 - 10:18 AM
#12

Hi guys

So I've been busy not had much chance to get out :(

However I have just finished installing a Mercury Taco to match up with the main engine so I can run some numbers and see where the engine is running. I also went for a height adjustable transom mount axillary bracket installed to the rear starboard transom. I have picked up an almost brand new Mercury 3.5hp 4 stroke long shaft for £250.00. It maybe a little light but a lot of people use them down here as back ups if it can push me along at 4/5 knots against the tide it will be fine for me and where I live/fish. It also has a tiller lock and throttle lock so I can use the main engine to steer if I want to troll.

If its not good enough I can sell it for a good return and upgrade hence the adjustable transom mount.
I'm hoping to get out one evening this week to test it all.

thanks all
Mike