Getting "more" from my 1971 Evinrude 9.5 hp

[DryFlyRy]

Hi, 2 days ago I purchased my first boat and motor... Ahem, let me rephrase that, my first FUNCTIONING, boat and motor (long story). She's a 14ft aluminum Starcraft with a 1971 Evinrude 9.5 Hp moving her along. It looks nice and clean and well maintained under the hood and seems to run alright (from what little i know)... I just have one simple (or not so simple?) question: according to my GPS my highest speed was 6 mph and average around 5.5 mph... for some reason I just expected a little more. Is this where I should be? My weight was myself (about 200 lbs) My dog (about 50lbs) a 5 or 6 gallon gas tank and a marine battery for an electric trolling motor. Are there any little tweaks I can do to this little motor to get some more push? I have heard some discussion on getting the boat to "plane" properly, but not exactly sure what that means or how to do it.

p.s. this site is great, I've been reading for about a year, this is my first post!

 

[F_R]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

At only 5MPH, that motor is not doing anywhere near what it is supposed to. Either that or the boat is a real dog (apologies to your live dog). The motor is probably running on one cylinder.

 

[DryFlyRy]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

the boat definitely doesn't seem very heavy, i can move it around pretty easily on the trailer by hand. How can i check to see if its running on just one cylinder? would peeking behind the spark plugs tell me anything? Should i just change them out anyways? I would have thought just one cylinder running would sound funny, like a stutter or something. I'm getting nervous, I've already had a big 115hp seize up on me on the first boat i was trying to fix up. Maybe I should take up golf.

 

[steelespike]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Disconnect one plug wire and ground it see if the motor will run.
If it runs do the other plug wire.It probably won't run.
You might check the plugs. One may appear really wet. If they are fouled
(really dirty)change them.

 

[Deanrt]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Does the prop extend below the bottom of the boat? The cavitation fin should be near or below the bottom. And for taking up golf............ I did just the opposite, and neither one is cheaper then the other. Go with your passion.

 

[jay_merrill]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

I agree that the motor is probably running on one cylinder. Either that or the high speed jet is fouled.

If your Starcraft is an early seventies, open bow type, with three rows of seats in it, I would offer the comment that I had a friend with one years ago. He had an Evinrude 18hp on his and it performed very nicely. I don't think your boat is going to go too fast even if it is running properly - I suspect it will plane with a light load, but not much over that. Replacing the motor with an 18 or 25 hp motor would probably be a better match.

 

[Chinewalker]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

I've run 9.5s and 10s on my 14-foot Starcraft tinny and it does indeed plane off nicely. Definitely check your spark situation as described above...
- Scott

 

[eavega]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

I have a Valco 14' aluminum boat for which I had gotten a 10 HP Johnson seahorse. Granted the motor was old (1960) and compression was probably a bit low, but it would only push my boat with me, trolling motor and battery, fishing gear, and 3 gals of fuel (estimate total weight at about 600 Lbs) at about 6 MPH at WOT. The boat was rated to a 25 HP motor. On suggestions from this board, I replaced it with a 20 HP seahorse. Now with me AND another large-boned fellow in the boat, plus all previously mentioned gear (I figure about 825 Lbs) I clocked the boat at 20 MPH.

I had also received advice to try to balance out the weight on the boat. The way I was set up, I was definitely stern-heavy with the fuel, trolling motor, battery, me, and the outboard all sitting on or near the stern of the boat. You might want to try to play around with shifting some of the weight around in the boat to see if that helps.


-E

 

[jay_merrill]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

I think the main issue with a 14' aluminum boat combined with a small motor is bottom type. The boat that I mentioned was a V-hull with a tapered bow. Typically, these boats take a little more engine to push.

On the other hand, a flat boat, or even one with a substantially flat bottom, will tend to plane much more easily, and require less power.

 

[DryFlyRy]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Ok, well i took a look at the spark plugs, both seem to be clean and dry

I can't test run it removing one wire as described just yet as i don't really have access to a nice big bucket of water or a hose here at my apartment, but will do so when I get a chance to bring it to the parents house. Also on that note, how do I go about grounding a plug wire? do i stick it on a bolt somewhere long enough to make contact inside the rubber cap? also the majority of the block is painted, so not sure what the best way to ground it is. But i can understand the theory behind the process.

The prop is below the bottom (see pic) not sure exactly what a cavitation fin is though... also, when i look at that picture, i notice that the motor/prop towards the bottom aren't exactly level/parallel with the bottom of the boat. It looks like I can adjust it so it would come down a little more and sit more flush with the transom. would doing that help at all? or should I leave it as it is?

The boat is actually i think somewhere in the late 60's. Does kinda have that taped v hull, and all the weight was in the stern (except my dog was bouncing around here and there a bit). So that could be it also. I just want to make sure everything is working properly and I am getting the most out of what I have. If it ends up the answer is "hey you have a 37 year old motor and an even older boat; 5 1/2 mph with all that weight is about all you can expect" then thats fine too... i will make sure both cylinders are fire though..

lastly, what exactly is the high speed jet? can i check to see if it's fouled easily enough?

 

[CATransplant]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Nah...when you get that 9.5 running right, it'll plane your little Starcraft boat just fine. I have the 12' version of it, and get 15 mph with a 6hp Johnson. You have a trolling motor on the back. Where's the battery? Right behind the rear seat, right? The fuel tank? Same place, right?

Move 'em. Put the fuel tank in front of the middle seat and the battery up by the front seat, or somewhere forward. Weight distribution is pretty critical here. Also, always have the trolling motor tipped so no part of it is in the water when you're running the outboard.

Looking at your motor, it looks to me like it might do well by moving the tilt pin one hole closer to the boat. Experiment with that setting, once you get your motor running nicely and the boat's weight balanced better.

I'd expect about 15 mph for your boat and motor setup. First step is getting the outboard running perfectly, though.

 

[TN-25]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

I think the main issue with a 14' aluminum boat combined with a small motor is bottom type. The boat that I mentioned was a V-hull with a tapered bow. Typically, these boats take a little more engine to push.

On the other hand, a flat boat, or even one with a substantially flat bottom, will tend to plane much more easily, and require less power.

This is very true.

If this boat and motor have been together for a long time I doubt that this pairing would have stayed together if such poor performance was delivered.


Dad used to have a 14' Nalco aluminum cartop powered by a Johnson 9.5. It was a substantially flat bottom, perhaps slightly rounded. Rated for 15 horsepower it gave pretty good performance with the 9.5, maybe 15 m.p.h. on a good day (GPS was not available to the masses back in the 60's & 70's.)

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Attached is a page from a 1968 Starcraft brochure with some specs and pictures. The open fishing boats did not change much for many years, so essentially your specs are there. The Super Star shown is a 14' with a '67 Johnson 20-horse on the back.

 

[TN-25]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Not to take away from the possible motor side of your performance question, but I just thought I would add the attachment for the 1968 Starcraft Sea Scamp. I believe that may be your boat. You mentioned that it is 14' and has 3 seats, that is what twigged me.

Moderator: No more frivolous attachements if I can help it.

 

[DryFlyRy]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

"TN" - yea that deff looks like my boat. Thats pretty neat!

So last night i took her out again... I moved the battery up front behind the first seat, and the gas can just in front of me (my gas line wouldnt allow much further), I also had one other passenger this time sitting on the center seat. I made sure the elec motor was completely out of the water and I had also adjusted the tilt back 2 notches so it looked even with the bottom of the boat.

the lake was perfectly still (the original speed test i did there was a little bit of wind) and with everything combined I got over 10 mph a some points! Averaged about 9.8. I brought a length of wire i was going to use to try the 1 plug and ground the other test while out there, but it was getting dark and i didn't really want to mess around with important things in the water in the dark, esp after noticing that my speed nearly doubled when making those few adjustments. but i will still do the test if you guys think it still sounds to like its running off one cylinder.

keep up the good advice guys! this site is great!

 

[CATransplant]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Yes, I think he has the Sea Scamp, not the Sea Star, based on the gunwale height. It's a bit lighter. I have a 12' version of that boat, relabled as Sea King and sold by Montgomery Wards. Starcraft made their aluminum boats in the 1960s. That's a fun fact for prospective buyers, since Sea King boats sell for quite a bit less than Starcrafts of the same age.

Mine is old, somewhat beat up, but every rivet on the boat is still tight and there are no leaks whatsoever. I have no problem recommending Sea King or Starcraft aluminum boats of that vintage to anyone. They handle the water extremely well, and are pretty fast with smaller outboards. Stable in the water, too. The construction is very good.

The only problem with the Sea Scamp line is that they don't drain well on the trailer, since the horizontal braces have no drainage gaps. They also do not come with transom drain plugs. They were designed to be car-toppers. The wet-or-dry shop vac gets some use after every rain. The plug is easily added.

 

[DryFlyRy]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

i did notice that about the drainage. mine does have a plug in the transom but sits just a fraction of an inch high enough to hold a small puddle, not to mention the puddles next to each of the braces, a little annoying, but hey, for $350 soaking up a puddle with a old towel each time is not a big deal to me.

 

[arcadiainc]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Have a 1970 9.5 Johnson on a 15'3" Herter's fiberglass open bow. Boat weights 220 pounds. With full load, two people and gear weight is about 800 pounds. She does 11.8 mph under ideal conditions. Just found out that I have the wrong prop on the engine. My prop does not have a rubber hub insert and she breaks drive pins frequently. Am thinking with the correct propeller the speed will remain about the same. The boat is rather narrow for the length and has a flat bottom starting about 1/3 the way from the bow. Relative to the 14 foot aluminum boats the speed seems to be about as expected.

 

[Bear 45/70]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Disconnect one plug wire and ground it see if the motor will run.
If it runs do the other plug wire.It probably won't run.
You might check the plugs. One may appear really wet. If they are fouled
(really dirty)change them.

Do NOT ground plug wires, even on an old points system. Either use a plug in the wire and ground the base of the plug or go buy a couple of cheap spark testers at Harbor Freight.

I agree that the motor is not right. Check the pitch of the prop. To much prop will lug the motor making the boat slow and can destroy the engine.

 

[Grem]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Some interesting information here, for a novice such as I am!
My boat is a 14' Delcraft (You plonker Rodney! LOL, excuse me) which came with a '72 Johnny 4hp. I have no idea how it should be set up or what it should do, but I know it goes faster than I can run, so I estimate abt 7-8 mph. Would that be about right, with two adults and 3gal fuel? The engine hadn't been used for at least 8 years and it wasn't until the second outing that it really cleared its throat (and I'd fiddled with the jets) and sounded 'right'. To start with it ran on one pot for a while which was obvious due to the increased vibration.
Here is a link to a couple of clips I uploaded to Youtube and I would appreciate any input from those with experience. On one of the clips it sounds like the engine is missing- but that's my old camera's fault, not the engine.

http://uk.youtube.com/watch?v=Jpin7r2ZO-I&feature=related

DryFlyRy- Does your motor 'rev-out' like mine?

 

[McGR]

Re: Getting "more" from my 1971 Evinrude 9.5 hp

Those 9.5s are good little fishing motors. However, they were notorious for exhaust leak problems that would cause exhaust gasses to enter the cowl and starve the motor of oxygen. You may want to try running the motor breifly without the cowl (aka hood, cover etc.) and see if it doesn't improve things.