1975 baja What prop

[BajaBoy]

I have a 1975 Baja. I think it was called the 14 but it measures about 15' 6". I put a evinrude 140 v4 looper on it with a v6 L1 type gearcase. the bigger case gave me more prop options and a higher gear ratio but still have plenty of power to push it. I'm still working on the setup and i'm looking for the right prop. Yesterday I ran a 22 raker2 prop 5600rpm doing about 67mph. I think it could be faster but the boat has BAD chine walk. The motor is stock right now so I don't wanna turn more than 6000rpm. I want to try a chopper prop I can't find one local. I'm scared to buy it without testing something similar. Would a raker and a chopper of the same pitch and diameter run close to the same rpm? And why don't I see anyone else with Baja's? Are they just not that great of a boat or are they all at the bottoms of the rivers?

[flabum1017]

I have an '85 16' Baja and have been told that anything over 60 is pushing it with these boats. They don't have a good pad. Mine starts chine walking at 60

[BajaBoy]

Yea I've been thinking about doing a hull mod and widening the pad. Someone suggested popping a mold from a crystal craft pad and use it. But what about the props? Will a chopper preform similar to a raker or does the over hub exhaust increase WOT RPM?

[flabum1017]

With an over the hub prop, you will need more height and preferrably some set-back. That boat needs bow lift, so a chopper with an 8" jackplate should do it..... as for pitch, I don't know.... I'd guess at 24", but you need to find someone to loan you a few to try

[BajaBoy]

It has plenty of bow lift with the raker. I'm running a 6" jakeplate and I had to raise the motor after putting the bigger gearcase on it. there is about an inch left to raise it but it doesn't have low water pickups so I'm leery of going much higher without a water pressure gauge. But I've never ran a chopper before so i don't know what to expect or how to set it up.

[David]

Your speed, rpm, and pitch don't match. Try putting your rpm and pitch into a prop calculator. Less than 10% slip is unlikely.

http://www.rbbi.com/folders/prop/propcalc.htm

Good steering would help you. With hydraulic steering, mine is easy to control. You should also check to see how solid your boat was. My 84 Baja needed a total restoration. Fortunately a prior owner paid for it.

2 owners ago, my 1984 16' Baja was drag raced with a V6, so they can go fast. Now it's got a 93 Johnson 100 HP. 57.6 GPS with a DAH 23 SRX. 4" manual jackplate. Prop about 3" below the pad. Prop height isn't critical. +/-1" doesn't change speed much.

For me, the SRX is a few mph faster solo than my thru hub Renegade.

For you, a 22 or maybe 24" chopper. Probably a small ear.

[flabum1017]

Your speed, rpm, and pitch don't match.


now that you mention it, :iagree:


My bubbleback crossflow V-4 ran 56 MPH @ 5600 RPM with the V-4 case...... unless he's running a different gear in the V-6 case he's using.


I also agree on the hydraulic steering..... a must

[BajaBoy]

That wasn't gps speed. I thought my speedo was pretty close but I guess not. Don't I look like a fool? Well I'll find a hand held and get some real #s this weekend. But as low as my motor is, I wouldn't doubt if the slip is very little... It's not much boat for that big prop. This gearcase is off of an Evinrude '01 225hp DI. I think it's the standard 1.86 ratio. I like hydraulic steering too but it's expensive. The dual cable does a good job of taking the slack out for now. Thanks for the advice. I still need to find a chopper though. I think this raker gives WAYYY too much bow lift.

[flabum1017]

I would guess you're getting between 55 - 60 out of it...

[BajaBoy]

:( ok you guys are right... 60.1mph with 2 people and 15gal of gas. I can't stay on it though. Wind catches the bow and I loose control. I was wrong about rpm too. After raising the jack plate to the max (still more than 3" below pad) it turns 6000rpm trimmed out. Will a chopper give me a better hole shot? I'm looking at a 24pitch. I'm also really considering widening the pad... I think it would help with the chine walk. Any other suggestions? Thanks for all the help so far.

[BajaBoy]

I forgot to mention the second person weighs about 80lbs

[staylor]

...and a chopper isn't. I ran a larger Baja SS186 w/140 cross flow about 25 years back. This was the small case and the boat ran best overall w/22 inch V-4 raker. It ran about 1 mph quicker w/23 inch SST-RX V-4 chopper, but hole shot was best with the Raker. This was a plain Vee- no pad, and chine walk would set in at about 52 mph, best speed was 54. I ran dual cable steering and could bump steer this well enough to keep the chine walk down. If I had the same rig today I think I'd try a 4 blade to see if that would tame the chine walk. Something like a 23 Trophy Plus would be interesting to try on your rig. I later ran a 175 V-6 on the Baj SS186 and did 63 mph w/24 inch Turbo II 3 blade, 61 w/22 V-6 Raker. The Turbo II was a bit smaller in diameter than the Raker and the boat really liked it.
Doug

[David]

Don't widen the pad, just practice more. Search here on chine walk. If you've got dual steering, the boat should be controllable with practice. Raising the motor might help stability, but watch your water pressure if you try that.

[pcrussell50]

This was a plain Vee- no pad, and chine walk would set in at about 52 mph, best speed was 54. I ran dual cable steering and could bump steer this well enough to keep the chine walk down.
Doug

i don't have a baja, but my 16' hull is an unpadded vee and looks like sidewinder/baja hybrid, sooo...

doug, you've helped me before when i thought i was getting 35% slip and such on my light 16 footer. as was suspected, my tach was all kinds of wrong. it was set on position "1" where my motor has 6 pickups, so you can see how that might be. when i thought i was doing 6000rpm, i was really doing 4000rpm. so i broke out a prop calculator and plugged in the 22" pitch from my raker, and an assumed 10% slip and wagged that i could get well into the 50's without fear of over-revving, even without a tach.

so i took her out and let her rip, with a portable gps in hand. guess what happened again and again right at 52 mph gps? mmmyep... she started walking. only i had everything going against me:

novice driver
single cable steering
no hot foot
throttle with right hand and...
steering and holding the gps BOTH with left hand, [stupid :o]
light, gutted hull, with me sitting right, AND battery on right, so NO attention to weight distribution, [will fix that next time out at the lake].

oh well. i said publically that i'd be happy with _anything_ in the 50's and I am. i'd just like to solve the chine walk and all will be good.

-peter

[staylor]

Peter, you've listed just about all of the basic problems that should be addressed to minimize chine walk. First thing is to get the hull balanced from side to side. Sometimes you may have to resort to the old trick of putting a 50 lb sand bag in the boat and moving it around to find the best balance point. Second issue is the steering. You may need to go to a dual cable so you can take out all the slack in the system- and you should check your steering gearbox to see if its worn- or maybe adjustable for slack. All cable connections should also be checked for slack. On an ideal set-up if you wiggle the cav plate you will find less than 1/16 inch motion at the connecting link to the steering before resistance is felt- in a perfect world this would be zero play. Also, on an older OMC motor you should check the torque on the engine mounts and also inspect the mounts for wear. Some of the link connections for the steering system may also be worn to an oval from lack of lube and these will have to be replaced too. The one thing I would not suggest is going to hydraulic steering in hopes of curing chine walk. I have a 17 degree vee hull currently- no pad and a 150 Opti with SeaStar hydraulic. I've modified the steering to get the slack down to about 1/16 inch total, but what I'm left with is in the steering rack and with an older dual cable system I could adjust this down to zero. But with hydraulic steering you can't. One other thought is the amount of steering torque you are feeling when the walk sets in. If you are feeling the boat pulling to one side the motor can be "crabbing", where in order to go straight with the torque you have to steer the motor slightly to one side, so its not pointing in the same direction as the boat. This is easily cured with a simple torque tab added to the skeg, adjusted in length so you have minimum torque at top end. An old trick for OMCs was to take the cav plate tab and move it slightly to the left of center when looking at the back of the motor. Then you mount the torque tab on the right side. This looks weird but balances the motor torque very nicely from low planing speeds to top end on an elevated engine.
Doug

[BajaBoy]

I will have to upload some pictures of my boat so you guys can tell me what you think. For the most part, it sounds like I've rebuilt this boat right. I guess I just need to find a faster hull if I want more speed. I really like this boat though. It is alot of fun!

[76baja18ft]

A 1975 baja shouldnt have any pad at all on it.. it more than likely is just a rounded bottom keel ....

[BajaBoy]

It has a squared keel about 4inches wide and 3 sets of chines. It is a fairly deep-v hull. I'm sure that is why 60 is about top hull speed. I was thinking that maybe if I widen the keel out, following the contour of the bottom of the boat, to the first chine and then go to the next chine, building it to the same thickness, it would help. Am I crazy or does it sound possible?