Long Shaft

[20lbSloughShark]

I got a big 16' aluminum boat with a 20" transom, and I have a short shaft Evinrude. I am certain the 18 hp is enough to plane this boat, but due to the short shaft, it just sucks air. I found this HSOforum (link below) that has all kinds of parts for my motor. I am a little confused on what I need to make my motor a long shaft. Is it just the parts in the box in the corner of the picture? Is there anything else I will need, gaskets, longer drive shaft? It seems too easy a fix to just install this 5" extension with those two screws, nothing is ever that easy.

http://www.lmmarine.net/pages/oemparts?aribrand=EVI#/Evinrude/18203R_1972/GEARCASE/28779/53067

[CAMAN]

You will need that, along with a longer drive shaft and a longer water tube, also new seals for the drive shaft. And you should probably get a new water pump kit installed while you've got everything apart.

If it were me I would sell the 18hp and get at least a 25hp. I've got an older large 16 foot Lund that I started with a 25hp Merc on and it would plane out fine with just me in it but difficult with 2 people. Now I have a 45 on it because of the planing issue.

[20lbSloughShark]

Easy for you to say, I love the 18. It runs better than my 94 ford explorer (it never did run good). Everyone keeps telling me to get a bigger motor, is it really a problem? It sure seems to make a lot of power. I have looked at 35 hp's but that's more money. Maybe I can come out even, the 18 is worth $500, maybe with a little shopping I can get a 35 for a little more? My dad has a 25hp Evinrude, side by side (in my old boat) they accelerated the same and kept the same speed. Even though is seems to have power, you might be right.

edit: even though it is a big boat, it is mostly hollow, just bench seats and thin walls compared to Lund; Lund boats are tanks. It cant be that much heavier than my dads 14' Lund, if at all.

[fishnowworknever]

When I had my 14' it had a 20hp Chrysler on it...not enough power at all. I bought a 40hp short shaft and I converted it to a long shaft with a used kit for $80. I replaced the water pump/seals as well.

It wasn't all that difficult to do, but i'd look for a bigger motor if I were you.

[20lbSloughShark]

I've done some research and found nobody makes a kit for them anymore. I've decided to find a long shaft lower unit. The problem is finding a long drive shaft. I love this motor too much to sell it. Will any lower unit (any year) from an 18hp Evinrude fit?

[marine_man]

Have you checked with outboard recyclers, Twin Cities Outboard or Tim's Outboard ?

marine_man

[20lbSloughShark]

I put a wanted add on a-sales-site, and already have 4 responses. 1 guy with a used kit 2 with a lower unit, and 1 that might be spam.

Has anyone else used an 18hp or 20hp on a light (but big) 16' boat?

[jasper60103]

I put a wanted add on a-sales-site, and already have 4 responses. 1 guy with a used kit 2 with a lower unit, and 1 that might be spam.

Has anyone else used an 18hp or 20hp on a light (but big) 16' boat?

No, but I have a '81 25hp Johnson long shaft that I don't use any more (hint, hint). It worked fine on my 16' semi V, but I ran into some problem with it idling. I have two other motors and just don't have the time to mess with it anymore...

[CAMAN]

Has anyone else used an 18hp or 20hp on a light (but big) 16' boat?

Oh, sorry, when you said "big" boat earlier it gave me the impression it was a heavy boat also. Mine is a 16 footer with casting decks, livewell, bowmount, etc. so it is heavy. Yours sounds now like it is juust a typical aluminum boat with bench seats(or similar)?

Id say now that it should work okay for typical use, but once you start adding weight it won't perform like it did when it was just you

[20lbSloughShark]

Yes it is just an aluminum shell with benches. I don't plan on adding much, just you basic stuff, seats, rod holder, etc. I wont be outfitting it with a live well or anything. I can say it is considerably bigger than the one in the picture. I'll post my own pictures of it soon. I have put a lot of thought into power, and I know it will plane just fine. If I have too I can make some easy adjustments, like a less pitch prop, or a hydrofoil. I really don't care about top speed.

[jasper60103]

Yes it is just an aluminum shell with benches. I don't plan on adding much, just you basic stuff, seats, rod holder, etc. I wont be outfitting it with a live well or anything. I can say it is considerably bigger than the one in the picture. I'll post my own pictures of it soon. I have put a lot of thought into power, and I know it will plane just fine. If I have too I can make some easy adjustments, like a less pitch prop, or a hydrofoil. I really don't care about top speed.

Sounds like your mind is set on converting that motor to a long shaft, which should be easy enough to do. Here are the parts you need to locate. Some time ago I seen a kit like this on a-sales-site for $125. Another option is to buy a dead motor for cheap. The extra parts may come in handy.

[20lbSloughShark]

I made a deal today, I'm swapping lower units with a longshaft (plus $50).

[20lbSloughShark]

Here's what I got, and I'm happy with it. Keep in mind the motor is as big as any 25; a 25 hood will actually fit on it. I took it out with three big people in it and it planed fine and was going 15-20 mph. Its slower than my last boat, but that was unnecessary. I am planning on painting the shaft extension piece and the whole upper part of the boat that blue color. I'm happy with what I ended with. Now you can really see why I wanted to save this motor. It runs as good as it looks.

[jasper60103]

Nice fishing rig.

[reinhard1]

looks a lot like my first boat, but i had a 9.9 evinrude on the boat. that was one nice motor. ran smooth and trolled perfect. i dont fish that many big lakes so that was just perfect for me. looks like you got yourself a nice rig. good luck.

[20lbSloughShark]

The biggest lake I fish is clear water. Any bigger is a trip, and I just rent a boat. The only thing that concerns me is the water output. At full throttle it used to spray water just fine, now it just kind of falls out (but still quite a bit). It seems like the water was not overly hot, and it still sprays good at idle. Since the water impeller is practically new, the extra 5" of hose must just limit water flow or something. Maybe the original water pipe was straighter?

edit: it sprays out the exhaust only, and cools the exhaust instead of having a separate pee hole. I think it is a cool Idea. Why don't they use this method anymore?

[boatfixer]

The exhaust is and has always been cooled by water. The pee hole, or water pump indicator is a very small amount of the total amount circulating through the system. Its simply a tap into the water jacket and through a hose, out the bottom cowling. Id say its merely 5% of the total water capacity? Not much is my point. The rest exits through the exhaust, whether its through the prop, exhaust port located at the back of the anti-vent plate and/or exhaust relief ports somewhere just above the waterline.

[20lbSloughShark]

I am sure glad I kept the Evinrude. I went fishing Sunday, I somehow accidentally ended up at west Sylvia's access looking for a completely different lake. At 8am water in the bottom of the boat was frozen. By 8:30 this was gone. So it was just above 30 degrees, with a carbureted 2-stroke. I pumped the gas, choked it, one pull, and it starts. I just put it in gear and go. With just me in the boat, it hauls [PoorWordUsage]! I must have broke 30 mph, maybe I can GPS it before the open water season ends. (deer hunting will make it hard). I am so amazed at the power, I made a video. This is just me calmly taking off, the wind is so strong I can barely hold the camera up. That little hick-up at first take off is just me re adjusting my hand. I also picked up some cheap dark blue spray paint. Some tape and 3 coats later, it looks great! I just painted the extension.

http://www.youtube.com/watch?v=4iEmU3UQ8K0&feature=youtu.be

,

[jasper60103]

She runs great. Nice video.

[20lbSloughShark]

There is just one thing bothering me. The water cooling the exhaust used to spray out, now at full throttle it just kind of gurgles. As I said before, there is still quite a bit of water, and it is not overly hot. Has anyone had this happen to them? The water impeller looked in brand new condition, and worked perfect before the conversion. It still sprays at idle. With the added 5" of water pipe, is there really any need for worry?

[jasper60103]

There is just one thing bothering me. The water cooling the exhaust used to spray out, now at full throttle it just kind of gurgles. As I said before, there is still quite a bit of water, and it is not overly hot. Has anyone had this happen to them? The water impeller looked in brand new condition, and worked perfect before the conversion. It still sprays at idle. With the added 5" of water pipe, is there really any need for worry?

Yea, I notice with my motor at WOT, the water just kinda pours/dribbles out the exhaust relief ports instead of a spray like at lower speeds. I put a brand new water pump and thermostat on this motor when I first got it. The engine is cooling, and been running it for two years now, so I know it's good.

Another thing to consider...After your conversion, the water pump is now 5 inches deeper in the water, and it should be working even better than before. And that may explain the difference you're seeing. If it's cooling, I wouldn't worry about it. Enjoy your motor.

[Surface Tension]

I don't think this has the newer type peehole.

On the mid section there is a hole the water will flow from.

If the water isn't flowing like it did before its possible the water tube is misaligned in the grommet.