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  1. #1
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    Default Which Prop? 40 hp Evinrude

    Running '62 evinrude 40hp.

    My head is swimming and I am in a daze with all the prop and pitch information.

    The problem:
    runs good at low speeds but at WOT it REALLY jumps in rpm's with ALOT less thrust. It feels like a spun hub but I have tried 3 props that are all alike and it does the same thing.

    The dilemma:
    Although the later models call for numerous sizes, the size in my parts book specifically calls for 10-3/8" diameter X 13-1/4 pitch.

    Has anyone heard of Propco Propellers?? They have really good prices and they swear up and down that I want a 10-1/2"X12pitch (I am running a fairly lightweight 1961 Red Fish 16' fiberglass closed bow Baylap).

    Also getting one clank at mid-range speed but I don't think it's slipping out of gear because I DO NOT lose thrust completely. Is this related? The folks at propco said there is an adjustment (but they want me to buy a prop first before they tell me).

    Thanks
    Shawn T
    WIchita, KS

  2. #2
    Lieutenant Commander oldcatamount's Avatar
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    Default Re: Which Prop? 40 hp Evinrude

    If you have the correct parts book for your motor, stay with what it says. That "clank" is something you should check into. First, check the gear grease in the lower unit. If it looks milky, you have water getting in there and that will need to be addressed with new seals. I doubt there is an adjustment on the shift linkage (but there may be) If not, the clutch dog is probably worn down and needs either replacing or "flipping".

  3. #3

    Default Re: Which Prop? 40 hp Evinrude

    Quote Originally Posted by Intermediate Mariner View Post
    Running '62 evinrude 40hp.

    My head is swimming and I am in a daze with all the prop and pitch information.

    The problem:
    runs good at low speeds but at WOT it REALLY jumps in rpm's with ALOT less thrust. It feels like a spun hub but I have tried 3 props that are all alike and it does the same thing.

    The dilemma:
    Although the later models call for numerous sizes, the size in my parts book specifically calls for 10-3/8" diameter X 13-1/4 pitch.

    Has anyone heard of Propco Propellers?? They have really good prices and they swear up and down that I want a 10-1/2"X12pitch (I am running a fairly lightweight 1961 Red Fish 16' fiberglass closed bow Baylap).

    Also getting one clank at mid-range speed but I don't think it's slipping out of gear because I DO NOT lose thrust completely. Is this related? The folks at propco said there is an adjustment (but they want me to buy a prop first before they tell me).

    Thanks
    Shawn T
    WIchita, KS
    Are you sure the motor is not cavatating, that is, is the prop too shallow in the water when the boat starts to plane?

  4. #4
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks for the replies guys.

    Yes the gear oil is milky but only after 3 trips to the lake- my prop shaft seal IS leaking because it had a double seal installed on the oil seal retainer so we left it (but I can see the oil leaking out from this point).

    The clank is I think the clutch dog slipping.... BUT I don't lose thrust and it may be just popping in and out. The parts I used were used (The best of 3 junk motors-those gears are expensive) but wear seemed minimal. I'm going to open it back up and have a look.

    Update on prop situation:
    I was using (according to number on prop PJ30) I believe a 10-3/8" X 12-1/2".
    ALSO: I cannot plane out no matter where the motor is set.
    It is fine in low to mid-range speed BUT as I increase to WOT, the mph stays the same but the rpm's go way up!!! I get no more thrust.

    I am estimating the boat at 1000lbs loaded down, although it's a 16' it's fairly skinny and short with only a 16" transom.

    So would my need be MORE pitch and possibly a bigger diameter? I believe I can run up tp 10-12/"X14" pitch on this motor.

    Any input greatly appreciated.

    Thanks
    Shawn T
    Wichita, KS

  5. #5
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    Default Re: Which Prop? 40 hp Evinrude

    One more thing,
    This boat's hull is flat bottom in the back with v in the front (with a dip-down on the bottom of the hull in the front) - looks like a typical 1950's boat.

    Prop guy says to go with 10-3/8"X13-1/4" and no more under any conditions.

    And as mentioned earlier, I am running a 10-3/8"X12-1/2" currently and it won't plane out - just revs high and won't increase speed (doesnt lose speed)... it's like it's not turning enough water, does fine at low speeds.

  6. #6
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    Default Re: Which Prop? 40 hp Evinrude

    Listen to the Propco guy. The 10 1/2 x 12 was the best prop for that motor on the average boat it was likely to be used on (16').

    I think your motor is cavitating (ventilating). How high are you running it? The anti-cavitation plate needs to be somewhat below the bottom of the boat with that motor.

  7. #7
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks FR.

    I pasted a photo below... as you can see the cav plate is right AT the bottom and not too much below it.

    Propco initially said 10-1/2"X12"... But after telling him (Peter) everything he thought maybe 10-3/8" X 13-1/4"...

    What are your thoughts?

    Thanks!

    Shawn
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  8. #8
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    Default Re: Which Prop? 40 hp Evinrude

    As far as the "clank" be sure the shift cable moves all the way.Most likely a warn dog though. The setup looks good. Is there a keel down the middle? Is it over size
    either width or depth.Is there a bailer hole in the bottom that might be disturbing
    the water in front or near the prop. It sure sounds like excessive slip or venting.
    Has the bottom been glassed or modified perhaps a little rough?
    See if you can find a 4 blade prop.You might see if a prop shop can add some cup.Is there any way you could lower the motor even if only 1/4" or so perhaps by removing some trim on the transom.To split gearcase does limit the height.

  9. #9
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks Steel.

    There is sort of a keel... BUT... it end about 12" from the stern and there is a flat "pad", supposed to make it easy to plane.

    Oversized? Not really, it's fairly narrow at 66" wide and shallow with a 16" transom.

    The bottom was glassed on each side where original bunk boards made an indention in the bottom.

    I cannot find a 4 blade prop for this motor.

    On transom trim I used 2 pieces of 1/8" angle aluminum so the max i could gain is 1/4".

    What will a "cup" do for me?

    Thanks!!!
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  10. #10
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    Default Re: Which Prop? 40 hp Evinrude

    A 1/4" isn't likely to solve your problem but it might at least get you up to speed.
    Is there a slight indentation(groove) in the bottom just forward of where it joins the transom? Also the grooves forward in the bottom could be causing turbulance especiually if they continue to the stern.Hard to tell how smooth it is;but if its kind of pebbly it might be causing problems.Did the prop ever work right?
    Adding cup to the prop will help it grip the water,reduce slip.
    Did you rework the transom? If you glassed the bottom and reworked the transom you may have added overall height to the transom.
    There are 4 blade props out there Diameter will likely be bigger and pitch probaly low.
    But diameter doesn't matter in this case(the more the better) and the pitch can be reworked a little.

  11. #11
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks again Steele.

    It does seem to have indention just forward of the pad (where the back keel roller is) but that's how it was.

    Don't really have any other grooves (some of that is stainage).

    It IS indeed a bit "pebbly" though (I used epoxy bottomkote and rolled it on).

    This is the first season on the water for me (this boat was a rebuild).

    The prop I have is the one I got with the motor (10-3/8 X 12-1/2). As mentioned before my parts book says 10-3/8X13-1/4 but i thought that to be odd since the boat type matters too (plus all other models list several props but mine only lists one).

    Boy, a cup sounds like a win/win situation.. are there any disadvantages?

    In your opinion, is a 13-1/4 pitch enough or do I want ot try the 14?

    Shawn

  12. #12
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    Default Re: Which Prop? 40 hp Evinrude

    When "standard" prop sizes are suggested its based on the typical application.
    10 3/8 X 14 is the highest pitch listed in the 62 brochure.
    I think that would be for a pretty light boat.I think a 13 1/4 would work fine.
    Once you get a grip you can adjust if need be.
    Only dissadvantage to adding cup is it may lower rpm not a problem if revs were high in the first place. Explain your problem they should know where and how much cup to add.You might try smoothing the bottom finish a little.
    My thoughts are that the down and dirty cure is probably to remove about an inch from the transom assuming it solves the problem then just use sticks add about 1/4" at a time to a point just before venting becomes a problem again.
    As long as the clamps have a good grip you can finish the transom and just use the sticks to set the height.My boat has about a 1" stick holding up my 50 merc.

  13. #13
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    Default Re: Which Prop? 40 hp Evinrude

    Well it's definitely pretty light. With motor off I can easily lift the stern off the trailer. I would say no more than 3 or 400 lbs max. The motor weighs 150. I added 1/2 ply floor. There is no way in the world that it weighs more than 700 lbs with a full tank. Plan to still add seats and bimini top but that's it. These problems all occured with 2 adults so I would say 1000 lbs at the most. Is that heavy?

    Also boat is pretty narrow at 66".

  14. #14
    Supreme Mariner Frank Acampora's Avatar
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    Default Re: Which Prop? 40 hp Evinrude

    Look again at the first photo! That hull has a NASTY hook in it which will affect performance. Before you go crazy with the engine and props, get the hull correct.

  15. #15
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks Frank,
    That is how the hull is... the front drops down quite a bit. I would never imagine why they designed it that way... it collects so much water down in that bubble I had to add a second bilge pump in there.

  16. #16
    Supreme Mariner Frank Acampora's Avatar
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    Default Re: Which Prop? 40 hp Evinrude

    Believe me! It was not designed that way. It is no accident that the hook is right at the roller. Years of sitting (probably with water in it and significant weight on it) and poor/soft/broken stringers have deformed the hull. Until you correct that and any other deformities in the hull, you don't have a snowball's chance in hell of getting decent performance.

  17. #17
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks for replying to my thread Frank.

    There is no question that what you said is true about sitting. I got this boat for free and the balsa core was mush. Where it rested on the bunk boards were dented in on both sides AND at the rear where the rear keel roller is was deformed as well. There was also a couple holes in the hull... it was in pretty rough shape (but I figured since it was free, heck). I had it flipped upside down for a year and thought I corrected all the issues.

    Are you referring to the rear or front?

  18. #18
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    Default Re: Which Prop? 40 hp Evinrude

    I hadn't noticed that spot.It sure could cause problems including an inability to get the bow up.It could also be introducing air under the boat interfereing with the prop.
    It appears the hook is near the front but how extensively it affects the shape of the bottom could cause all kinds of problems.If there is a similar depression near the transom that also could cause serious handling and prop grip issues.
    Hope you can solve the problems.

  19. #19
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    Default Re: Which Prop? 40 hp Evinrude

    There was an indention just forward of the rear keel roller (behind the keel and forward the pad) from years of sitting but I filled that in with several layers of solid glass... it's smooth and even now.

    I have 4 adjustments on the motor. With the motor all the way out the bow never touches the water! All the way in and the bow is shoved so far into the water that it thrown a pretty extreme splash over the front. In between does fairly well. Cannot plane out though at any setting because at WOT the rpm's rev way up (starts to try to plane but not enough speed).

    I ordered a 10-3/8X13-1/4" prop WITHOUT a cup (because it was 30 bucks extra on a $60 prop)... since I didn't get the cup should I have got the 14 pitch since cup increases pitch?

    Thanks

  20. #20
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    Default Re: Which Prop? 40 hp Evinrude

    It is incourging it responds to trim.But that gig hook near the front may be introducing air under the boat.
    Its possible a new prop will solve your problem as some used props can be under sized from wear and may be less than perfect from use and repair over the years.
    In my opinion you needed the cup to combat your venting problem.Other than being new I don't think the 14 is your solution and it could endup being too much prop if it does work.
    Stick with the 13 1/4 for now

  21. #21
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks Steel!

    I figured I can add the cup later since we have a prop shop here local.

    The props I have are 10-3/8X12-1/2 so I hope the 13-1/4 is enough but I bet I'll need the cup. I seen around 200 rpm's per inch and this motor seems to rev way more than 200, possibly closer to 1000! Thats why I thought get the 14. The 12-1/2 performs very poorly.

    Going back to the front: I pasted a photo from the brochure below. You notice the front... thats how these boats are, there is nothing out of the ordinary up front. The dip is part of the hull.
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  22. #22
    Supreme Mariner Frank Acampora's Avatar
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    Default Re: Which Prop? 40 hp Evinrude

    NO, No, No! That's just the way it appears from the angle of the photo in the literature. Again, NO boat is ever designed with a hook in the keel--at least a hook that bad and in that position. On your hull, the keel should be (almost) perfectly straight from stem to stern. (I have seen a number of hulls that end the keel somewhat forward of the transom but again all have had straight keels.)

    And, no boat is ever really free. Oh, you may acquire one without spending money, but one way or the other you will pay for her.

    I had to search a bit, but notice how because of the photo angle, this boat also appears to have been designed with a hook in the keel about midship? It is perfectly straight.
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  23. #23
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    Default Re: Which Prop? 40 hp Evinrude

    Thanks for the input Frank but the hull is straight... it may just look that way in photos.

    UPDATE:
    The prop came in from propco (but watch those guys... they have one price on their website and then it's $20 higher and they say that their server uploaded the wrong price list but when you check back in a week the price is still wrong... use caution when ordering).

    The 13-1/4" pitch prop helped ALOT (I should have ordered the 14 but he talked me out of it... I plan to add a cup now which as I understand adds pitch).

    I believe it may be cavitating. It seems to need to be in the water more. Take a look at this video. (http://www.youtube.com/watch?v=0zfClpS7uEI) You will notice the anti-cav plate is just above the water which may mean that the prop is turning the surface water and mixing with air? ALSO: The side water inlet is OUT of the water so thus I also have no spray at high speed.

    Thanks!

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