Which prop for my Force 85hp? Pic Added - Question on New Prop

[UtahBoating]

Hello,

I have been out of the boating arena for several years....hence 7 years since my last log in. I recently purchased a 17ft bayliner with the Force 85 (single exhaust model). The boat runs well enough but I have been going through doing a ton of maintenance just because I am anal like that. When I had it out on the water I was a bit disappointed in the top speed, it had its moments but for the most part seemed a bit flat on the top end. For starters the trim was adjusted all the way to one side making me have to fight to steer it all day, I didn't realize this until after I got home and immediately straightened it out. The reason I bring this up is I am not sure if this would affect speed since I was fighting with it all day.

On to my question. I pulled the prop and it is a Michigan Wheel 15 pitch. The boat came standard with a 19 pitch according to the owners manual. I am going to buy a new prop. Should I go 17 or 19 is my question? I want to be able to pull a kid around on a tube occasionally, my wife water skis on 2 skis (not slalom), and other than that we like to cruise around the lake mostly.

Thank you for your recommendations on which to buy. Also if you have any pointers where to buy single exhaust props for this engine I am all ears, I have only found a couple of places online that sell the single exhaust model.

 

[Frank Acampora]

I think a 19 pitch on a 17 foot boat will be too much. More likely a 17 pitch would be closer to correct. HOWEVER: the only sure test is to check RPM. They should be between 4500 and 5500.

Look up Chrysler Force propellers on ebay There are some there. No need to buy new. Again, However, you need not be limited to single exhaust props. The engine will run very well with thru hub exhaust props AND there is NO difference in performance. You can use some Mercury props from gearcases with the small diameter--4 inch

Regular Mercury props are too big 4 1/4 inch diameter at the hub and will interfere with the gearcase.

 

[batman99]

My previous Force 120 on Bayliner 1700 loved its 4-blade much better than normal 3-blade.

Especially for water sports - like tubing and skiing.

Your Force 85 on Bayliner might like a 4 blade prop better as well.

 

[UtahBoating]

Wow quick replies, thank you. I have searched eBay for force props and most on there for the dual exhaust which are 4 1/4, if I understand correctly I need the 4 inch version. I did not know those older Merkc props from work I will look for some of those as well. I would prefer to buy used if I can find some.

 

[batman99]

iBoats online store ( re: http://www.iboats.com/ -> prop section ) sells reasonable priced new props as well.

 

[SkiDad]

Michigan prop. 072107

 

[UtahBoating]

Michigan prop. 072107

I ended up ordering this prop. Should be here on Monday, can't wait to give it a try next weekend!

 

[UtahBoating]

No Title

I went to put the new prop on today. It is really tight. Is this normal? I didn't even dare put it on all the way. My current prop I can slide on and off by hand. The new one I will have to use a mallet or tighten the nut to get it on all the way.

Also There is a washer/spacer thing (sorry don't know the technical term) that goes on first then the prop - see photo. I am afraid if I force this in the new prop it will never come out. Suggestions?

 

[SkiDad]

something is not right -that prop should fit - they must have sent you a defective one or the wrong prop - do you have pics ?

 

[UtahBoating]

It would fit, it's just really tight I'm thinking maybe if I take a wire wheel to the powder coating that it may fit better. Or do you think I'm better off contacting the manufacturer and sending it back.

 

[SkiDad]

i would swap it with another or return. not sure a 17p is going to be faster for you at your altitude.

 

[Frank Acampora]

Have you tried test fitting the thrust washer into the prop hub with the prop off the boat? Prop hubs and thrust washers are standard sizes from engine brand to engine brand so the thrust washer should fit into the prop hub. Second: Did the prop come with a plastic ring on the back? Some brand props are designed to fit multiple engines and have a plastic spacer ring the seal the gear case. If so get a screwdriver and force off the plastic ring the prop should now fit into the gear case without forcing.

If possible, a couple of photos would help.

 

[jerryjerry05]

If the owners manual says 19 I'd get a 19.
The 15 was good for tubing and skiing.
The 19 will get the speed and performance you need.
But if you carry a lot of people(chunky) and stuff go with a 17

 

[UtahBoating]

Well I won't be send it back, I took a wire wheel and removed the paint on the inside where the thrust washer goes and it fits just like the prop I took off.

 

[UtahBoating]

Frank, could you share some details on where I could find a Mercury prop to fit this motor, everything I find online via Ebay or other seems to be for a 4.25" gearcase. I saw in another post you can fit a Vortex prop to this motor but I can't find the details on how to do this, it doesn't show any hub kits for my motor.

 

[Frank Acampora]

Well, it has been a while but I remember I had a Vortex prop that came with a plastic ring to build out the hub to a Mercury gear case. The ring can be pried off and then the hub will fit a Force gear case. NOW: The Vortex also has three or four webs inside the prop that connect the inner hub to the outer hub. These webs will contact the anode on early Force engines and the simplest way to make the prop fit is top remove the anode Later Force engines had a much flatter anode and I am not sure that that one needs to be removed. Dual exhaust lower units do not have the interfering anode.

Of course, me never taking the easy way, I chucked the prop in my drill press and using an end mill, milled the webs down until they cleared the anode.

Mercury did make a "small gear case" 90. Props for this engine will fit Force engines. If you do not have a dual exhaust lower unit you can use other Mercury props simply by cutting off the flange that plugs into the Mercury gear case. There will be no loss of performance if you use a thru-hub exhaust prop versus a closed hub (on an single exhaust).

 

[UtahBoating]

So to clarify, does this mean I could use a merc prop for a 4.25" gearcase if I am willing to cut the flange off? I appreciate all your feedback on this, between you and this forum and my clymer manual I'm quickly becoming a force engine expert.