Help with outboard depth setting

SXRguyinMA

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Aug 22, 2012
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Hi all,
I just got a 1983 Baja 16' with a 70HP Evinrude. It hadn't run in a couple years but I went through it and got it in the water yesterday. I noticed on tight turns the prop seems to come out of the water enough to start cavitating. It's go no power trim and I tried putting it on the lowest trim setting and it helped a bit but it still does it. The motor itself can go about 1" lower where it mounts to the hull so I might try that next. IT's got an aftermarket whale tail shaped plate (ride plate or something of the sort I'm assuming) that's bolted to the drive housing. My question is what is the normal prop depth setting? Although if I drop the motor as far as it can go and it still does it then what are my options? Thanks!

Will
 

Texasmark

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Dec 20, 2005
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Re: Help with outboard depth setting

Yes dropping it will help. Speed will fall off somewhat but you will reduce your opportunity to ventilate. Problem with that and dropping to the lowest hole, and the addition of the whale tale tells me that you will be plowing and not realizing your boat's potential. Plowing is where the front (bow) of the boat is forced in the water by the pitch of the engine. It not only reduces your speed, but a lot of times makes steering difficult...boat wants to go where it wants to go and fights you at the steering wheel.

Better choice would be to get a cupped prop which resists blowout and preferably a SS high perf prop. I used to run a 70 Rude on a 16' bass boat and jacked up as yours, no whale tale, 19" SS prop would fly.

Mark
 

SXRguyinMA

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Re: Help with outboard depth setting

Well on the lowest trim setting it doesn't seem to plow at all, in fact is shoots right up onto plane and cruises rather nicely. Steering is tight but it doesn't seem to fight it at all, it leans in and turns. If it matters the boat is a tri-keel, or partial tri-keel as the side keels aren't very deep, but they seem to hook up in a turn and help it out a lot. I mainly plan on using this boat for cruising and pulling the occational tuber. Would removing the whale tail and dropping it help or should I leave the tail on? Also what pitch prop would you recommend? I've got no idea what's on it ATM. I can get some pics of the boat/engine/prop this afternoon if need be.
 

steelespike

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Apr 26, 2002
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Re: Help with outboard depth setting

Typically the anti vent plate(just above the prop) should be about even with the bottom of the transom to about an inch above.
If the motor is too low the Whale Tale will drag in the water at speed slowing the boat and causing it to lay down too flat.
At speed about half of the boat should be out of the water.Some very carteful pictuires showing the anti vent plate in relation to the bottom and the mount to the boat, also the prop.
 

SXRguyinMA

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Aug 22, 2012
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Re: Help with outboard depth setting

Here's pics of the setup. The whale tail does seem to be in line with the base of the hull (this is with the motor in it's lowest trim setting). I also noticed when I let it down that oil is coming from the prop shaft. How hard of a job is it to replace a prop shaft seal?

SANY3207.JPG

SANY3208.JPG

SANY3209.JPG

SANY3210.JPG
 

steelespike

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Re: Help with outboard depth setting

More than likely that "oil" Is actually exhaust residue.It probably smells gassy.
 

SXRguyinMA

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Re: Help with outboard depth setting

That was my first thought - but the oil is also coming from between the prop and housing and it's green and thick - it's gotta be the lower end oil.
 

jestor68

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Jun 12, 2012
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Re: Help with outboard depth setting

Drop the motor one hole on the transom.

Replace the prop shaft seal(have a mechanic do it) as it is leaking. You are in danger of running your lower unit out of oil. A leaking seal also lets water in. Drive gears don't like water.

Remove the Stingray thing.
 

SXRguyinMA

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Aug 22, 2012
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Re: Help with outboard depth setting

OK I've only got one more hole to drop it so I'll go for that. As far as the seal goes I'm a mechanic by trade. I've worked on everything out there powersports-wise except for outboards, but if it's relatively simple I'll save the $ and pick up a seal and do it myself. I'll also pull off the whale tail.
 

jestor68

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Re: Help with outboard depth setting

There is probably a U -Tube video that takes you through it. :)
 

Texasmark

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Re: Help with outboard depth setting

Before you jump to conclusions ensure that you have a prop seal leak. Remove the prop and inspect around the prop shaft and the inside of the exhaust tube. Course if the oil it thick, or if you pulled your LU plugs and found that your fluid was low, or contained water then you certainly have that problem. With 2 cycle engines mixing fuel, it is normal to have some oily residue drain down from the mid section.

On the tail, if you had a flat transom you would be in better shape. Yours is complicated and as Steel said, it can interfere with the performance of the boat.

On not plowing, being a tri-hull (as they are called around here) it could mitigate some of what would be plowing with a mono-hull.

Mark
 

SXRguyinMA

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Re: Help with outboard depth setting

If you look at picture 3 you can clearly see the dark green line of oil coming from between the prop and housing and i thappens to be the same color oil I topped the lower unit off with before I put it in the water lol. I'll pull the prop and inspect just to be sure though.

I'll get that sorted, drop the motor to the lowest setting and take off the whale tail and seew hat happens :)
 

Texasmark

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Re: Help with outboard depth setting

OK I've only got one more hole to drop it so I'll go for that. As far as the seal goes I'm a mechanic by trade. I've worked on everything out there powersports-wise except for outboards, but if it's relatively simple I'll save the $ and pick up a seal and do it myself. I'll also pull off the whale tail.

I have dug mine out without removing anything but the prop and thrust washer. Takes some time, but so be it. If you only change the outer seal, you don't even have to drain your LU oil. If you do both, then yes you have to or it will drain all by itself when you break the inner seal loose.

Mark
 

SXRguyinMA

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Re: Help with outboard depth setting

I'm going to change the oil anyways as it's been run with a leaky seal so chances are there's water in the lower end as it sits now, oil is cheap and better safe than sorry.

I've been looking at various kits online and it seems that all 70HP Evinrude's have the same seal/gasket set from the late 70's to early 00's. Is that true? I'm used to everything else in the powersports world changing every 3-4 years.
 

steelespike

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Apr 26, 2002
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Re: Help with outboard depth setting

I can't swear to the seal and gasket set but if you look up OMC fuel system and ignition parts you'll find the same parts cover not only many size motors but many years.
 

jestor68

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Re: Help with outboard depth setting

I believe that the 70 and V-4's share the same gear case, so the parts to fix it should be fairly common.
 

SXRguyinMA

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Re: Help with outboard depth setting

Ok so I dug into it today. I popped off the prop and the outer seal was bone dry, so I'm assuming it's not leaking from there. I removed the 4 bolts and pulled out the bearing carrier. I replaced the outer o-ring and then I noticed that 3 of the 4 o-rings on the bolts were completely torn and falling apart. I replaced those as well, put it back together, refilled the oil and let it sit. No leaks! At least it was an easy fix :)

I also removed the stingray but I haven't had a chance to drop the motor yet. I'll take it out without the stingray and see what happens. Thanks guys for all your help!
 

V153

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Re: Help with outboard depth setting

I believe that the 70 and V-4's share the same gear case, so the parts to fix it should be fairly common.
Not to nitpick, but just to clarify. The gear cases are not the same. Easiest way to tell them apart is the inlines have 3 water inlet holes per side where the V4s have 4. However yes they do share several common parts.

Glad you got it sealed up. Might not be a bad idea to pressure test? Bajas are fun old boats. Good luck with it.
 

SXRguyinMA

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Aug 22, 2012
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Re: Help with outboard depth setting

Well so far so good, haven't been able to pressure test it yet. This old Baja rips - I was thoroughly impressed the first time I cracked her open. Now I just need to get it back int eh water and try it without the stingray and see if it's any better at keeping the prop in the water on hard turns
 
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