Bigdaddyzeke

[bigdaddyzeke]

I just bought a 1988 force 85hp outboard with single exhaust.My question the engine came with a 13 1/8 x21" Ballistic stainless Prop.Will this work on this motor.
Thanks Bigdaddyzeke

 

[jerryjerry05]

Re: Bigdaddyzeke

It depends on the boat:size,weight?
The RPMs at WOT.
Most boats that use Forces usually have the max of a 19p.As low as a 13 on a pontoon.
Smaller speedy boats would use a 21p.
Post a pic of the boat after the motor is mounted.
Make sure the shaft is the right length for the transom.
I don't usually follow the prop section so if no one helps send me a PM.J

 

[Frank Acampora]

Re: Bigdaddyzeke

A while back I did a comparison of Ballistic to other stainless props on my Chrysler 90 (very similar to your Force 85) and posted it here. While the 21 Pitch Ballistic will be too much prop on your engine for any but the smallest boat, it will give acceptable speed. The problem is that your engine will probably be loaded down below the recommended operating rpm range of 4500-5500 at wide open throttle. The engine will "lug" and you may experierience carbon build-up.

As an example, on my 14 foot go-fast with a Force 125, the Chrysler racing cleaver prop turns 5900 rpm and 60 MPH. A 13 X 21 Ballistic stainless turns 4500 and still delivers 60 MPH.

So, while the Ballistic may work on your engine and hull combination, it may not be the best prop for it. Certainly, I would expect that it would not be correct if you wanted to water ski. It would be acceptable for tubing and probably wakeboading though.

Ballistic is a very well made and nice looking prop but in your case, I would most likely save it for a spare and pick up a 17-19 pitch prop

You really need a tachometer and need to determine what the wide open throttle rpm is. It should be between 4500-5500 rpm and preferably on the higher side --say 5000-5500.

Please post some photos of your prop off the engine and the prop shaft. Reason? I needed to modify my thrust washer to get enough room to fit the 21 pitch Ballistic. I would like to see if yours has been modified or if the previous owner notched out the exhaust snout for clearance. These photos show what I needed to do and the clearance from the blade to the snout. Note that the circular anode shown at the far left of the last photos is NOT used.

 

[bigdaddyzeke]

Re: Bigdaddyzeke Ballistic Prop

Re: Bigdaddyzeke Ballistic Prop

Thanks Admiral and Vice Admiral.The 85hp Force did come with a Boat it a Maxim 18 ft SR3.I don't have Pic of the prop off the motor but will take some and post.I have started the engine in the driveway after putting in new water pump and installed a p outlet copied from iboats.I did put the engine in forward and reverse the prop made no noise.The boat looks good from the out side but water soaked inside.The floors were rotten and foam was soaked.I have not had the boat in the water.I have checked the hull,no cracks. I'm down to taking out the stringer
Bigdaddyzeke

 

[jerryjerry05]

Re: Bigdaddyzeke Ballistic Prop

Re: Bigdaddyzeke Ballistic Prop

Take lots of pics of the restore.Post them in the restore section.J

 

[steelespike]

Re: Bigdaddyzeke Ballistic Prop

Re: Bigdaddyzeke Ballistic Prop

Sounds like a rebuild is in order.You need to be very careful to maintain the hull shape.
The bottom is likely allready pushed out of shape especially if it over hangs the trailer.
You also may want to check the transom for rot.Shake the motor front to back and watch for movement.

 

[bigdaddyzeke]

Re: Bigdaddyzeke Ballistic Prop

Re: Bigdaddyzeke Ballistic Prop

Took pic of the prop today.I do have pic of the deck and foam removal. I will post later I have to sort dates out.Here the prop pic. The prop has about 1/4 clearance at the top,spin good. Thanks

Bigdaddyzeke

 

[bigdaddyzeke]

Re: Bigdaddyzeke Ballistic Prop

Re: Bigdaddyzeke Ballistic Prop

steelespike,I did check the transom.I shook it real hard looks ok.Now you have me worried about the shape.I did't take the top off.I did tar the deck,foam and seats out working on stringers now.I'm 70 yrs old so some days quicker than others. I plan to make this a fishing boat.I'll put Todd seat in, redo the bow for wife or grandchildren.I have ordered all new vinyl and foam backing.I've ordered my fiberglass ,foam and decking.
The wood in the boat was rotten,foam was soaked,stringers rotten along where old seats were and rotten on cross members. where contact with stringers. so i'll take out stringers.Not easy some-days hard to bend over.

Thanks bigdaddyzeke

 

[Frank Acampora]

Re: Bigdaddyzeke Ballistic Prop

Re: Bigdaddyzeke Ballistic Prop

Big daddy: Thanks for the photos. They showed me what I was curious about.

That's the exact prop I have--same numbers. I can almost guarantee that it is too much pitch for your 85 on your 18 footer. There will be two results: 1. At idle, the high pitch will lower the idle speed, possibly below a reliable idle. 2. Top RPM will not be within the manufacturers quoted range. This could lead to carbon build-up. Correct pitch should be somewhere around 17. HOWEVER:

You really should consider installing a tachometer since without one, you have no way of knowing where you are. Like taking a trip without a map--Oh, you may still get there but you certainly won't take the best route.

I see from your photos that the previous owner countersunk the back of the thrust washer to move the prop backwards on the propshaft and clear the exhaust snout. I entertained that idea but rejected it as weakening the thrust washer. Thus: I elected to go with a split collar on the shaft.I used the thrust washer on the front of the prop as a nut and washer locator.

 

[bigdaddyzeke]

Re: Bigdaddyzeke Ballistic Prop

Re: Bigdaddyzeke Ballistic Prop

Frank.Thanks.I'll order a13x17 prop.Do I need to order a split collar.What is a split collar?I have another question,the U.S.Marine shifter is new per previous owner the wire going forward are purple,red,black and orange .I do have a tach.
Thanks bigdaddyzeke

 

[bigdaddyzeke]

Re: Bigdaddyzeke

Frank,I went back and looked at your pictures,you have alot more pieces than I.
Bigdaddyzeke

 

[Frank Acampora]

Re: Bigdaddyzeke

Whoa! Whoa! Since you do have a tach, BEFORE you order another prop find out what your wide open throttle RPM are. That way at least you know about how far to go. Right now, it is just a guess. Better to make haste slowly rather than jump to confusions.

Yeah, I do have more parts. The split collar is available from Fastenal but it is expensive--35 bucks. A split collar is exactly that: it is a shaft collar (in this case all stainless) in the size of the shaft, split in half and held together on the shaft with two allen head capscrews. It can grip the shaft so hard that it will not slip. Go back to my photos and you can see it on the prop shaft in the first photo. No, you do not need to order one as long as your thrust washer is not broken.
I am a bit overly cautious and as I said, I elected to use a split collar instead of modifying the thrust washer.

The reason for the extra pieces is this: There is a slight land on the shaft where it enters the spool and seal. I slid the split collar back to this land strictly to ensure that it would not slide back during operation (I told you I was a bit overly cautious). HOWEVER: When slid back this far, the prop hub contacts the gearcase housing so I needed to add two spacers in front of the split collar. The piece with the two screws (at the extreme left) is the anode I mentioned which must be removed and can not be used with this prop.It is not an essential part unless you use the engine in salt water. Even then, you could attach a flat zinc anode to the cavitation plate.

I hear you on the difficulty to bend over---66 with arthritis and some days I can't use my hands at all. Growing old sucks---but I don't like the alternative LOL

 

[bigdaddyzeke]

Re: Bigdaddyzeke

Frank thanks for your response.I will try the prop first.An yes I was in the boat all day boy do I feel it tonight but its fun gives me smothing else to do.I'm taking tomorrow off,going to throw my nets see what I catch.I do live near salt water about 8 miles away..

thanks again bigdaddyzeke