OMC or AFTERMARKET Prop????

[Boilermaker]

I need a new prop for my 18ft Deep Modified Vee with Johnson 115 (fresh 1978 model>>PLEASE see my post "NEWGUY PROP???") The engine ORIGINALLY had a 13x19 and ran well>>>but that was the old "elephant ear" style OMC with no cupping>>now that prop needs a new hub, and I don't think its worth the cost.<br />I tried a new 14x19, and had a slow holeshot when loaded, But loved the topspeed>>even at 4800rpm.<br /><br />I am now running a "newstyle" 14x17 Alum OMC prop (shop loaner) and seeing 5300RPM with good throttle responce.<br /> I would like to step up to a STAINLESS prop but don't know if I should stick with the OMC, or would be better off with an aftermarket prop??? IF an OMC>>>Which style (I see on the web page they have a few different styles S.S.)???>>If aftermarket>>>should I get a VENTED hub or not???<br />I see a few aftermarket props that are 13x19 or 13.5 x19 ect...>>>would that be closer to the original in terms of holeshot and still have good topend??? How are the props that have seperate hubs and blade castings??? Seems like a good way to have differant setups for loads.<br /> I am asking for recommendations as to what to buy, NOT abt. trim tabs ect. (I will be removing my STINGRAY plate though)>>>I need to get the prop dialed in first (have to return the shop loaner). I use this boat as a family runabout, fishing bays, ocean inlets, and calm ocean days>>> and towing my boys around on tubes.<br />SORRY this is long, and THANKS for any help!!!<br />

 

[Dhadley]

Re: OMC or AFTERMARKET Prop????

Going to a SS prop you will most likely need to raise the motor on the transom. Looks like the decreased drag would benifit your rpm's also. <br /><br />We have had great success with the Stiletto props. Reasonably priced and do as well as, if not slightly better than, a Raker. If we were setting up the test session we would look at the present set up to establish our baseline. If you post the true (GPS) top speed with an average load, we can calculate slip % and see where we're at.<br /><br />I'm leaning toward a Stiletto 17" 3 blade but you may be able to swing a 19" depending on how your hull reacts to an increased X dimension.<br /><br />Good luck!

 

[Dhadley]

Re: OMC or AFTERMARKET Prop????

I just read your other post. Everything you say indicates the motor is begging to be raised. Especially with a larger diameter prop and/or one with more bite. That also explains the excessive positive trim angle.<br /><br />Good luck!

 

[Boilermaker]

Re: OMC or AFTERMARKET Prop????

Thanks Dhadley, >>><br />Forgive my ignorance on the subject>>>but what is the X dimension??? And what is involved in rasing the engine??? I see that there are a few holes on the mounting bracket of the engine for the top bolts, and slots for the lower (I think thats how its set, I'm not near the boat right now)and the top of the bracket hangs on the top of the transome.>>>Is it just changing the mounting bolt spot rising the engine???>>>Something I can do at home>>>or is a trip to the shop in order????<br />Thanks

 

[Boilermaker]

Re: OMC or AFTERMARKET Prop????

Also, Is there a "standard" position/hight of the anti-vent/cavitation plate on the engine in relation to the bottom of the transome???

 

[AUGIDAWG]

Re: OMC or AFTERMARKET Prop????

If you want a better hole shot, use your boat in rough water, and want to get rid of your Stingray, you may want to concider a four blade.<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=034865 <br /><br />With your engine, if you get the 17" pitch, you won't be turning 6000 rpm like my 200 Johnson.<br />More like 5000 rpm.

 

[Dhadley]

Re: OMC or AFTERMARKET Prop????

The correct engine mounting height (X dimension) depends largely on the hull design and the propeller design. There are a lot of influencing factors also like fins (or no fin), size of the fin, load in the boat, set back and so on. <br /><br />Your motor is mounted as low as it can be now. Yes, you can probably raise the engine at home. A lift of some sort makes the job a ton easier. Before you spend money on a prop, play with the height just so you get a better understanding of what we're dealing with. It costs nothing but time (and a tube of sealer) and can be a lot of fun. Just be sure to reseal the bolts so no water gets in the transom.<br /><br />Since the motor is all the way down, move the bolts to the third holes. Even to the fourth. That may be too high for your aluminum prop but you will see what a difference it makes.<br /><br />What neat homework!

 

[Boilermaker]

Re: OMC or AFTERMARKET Prop????

HOW HIGH is too HIGH??? Don't I have to be conserned about the cooling water pickup??? I don't have a water pressure or temp gauge on the engine.

 

[Boilermaker]

Re: OMC or AFTERMARKET Prop????

How can one type prop be a BOW LIFTER, and another a STERN LIFTER???? Don't they provide thrust along the same plane??? <br /><br /> ALSO>>>> what would be the BEST type of sealer for the engine bolts ????<br />THANKS

 

[Boilermaker]

Re: OMC or AFTERMARKET Prop????

So where are all the PROP experts??? <br />Only kiddin'>>>>but I DO need an answer!

 

[DJ]

Re: OMC or AFTERMARKET Prop????

BM,<br /><br />Prop changing will not do you a lick of good if your engine is not set up right. Even at 5300 rpm, that engine is LUGGING. Not good. Your top rpm should be 5500-minimum.<br /><br />Follow Dhadley's advice. Dhadley is the resident expert on performance boats/props/setup.<br /><br />Once you see how the engine reacts by raising one notch, you'll have a much better idea of how different props are going to react. As Dhadley said, it only takes time/muscle and a tube of sealer. Save your prop money for the RIGHT one.

 

[Boilermaker]

Re: OMC or AFTERMARKET Prop????

Maybe 5500RPM is lugging on the newer engines, but it is the top recommended rpm for my 1978.<br />I will try lifting the engine on the transome>but I don't have a GPS to accurately track speed. >>>Again, THANKS

 

[Hooty]

Re: OMC or AFTERMARKET Prop????

I spin my 1976 200hp 'rude 6200rpm on a regular basis and it loves it. It just hums.<br /><br />c/6<br />Hooty

 

[DJ]

Re: OMC or AFTERMARKET Prop????

BM,<br /><br />Do what you want to do. If you do not want advice, don't ask for it.<br /><br />It has been proven that the older OMC's could easily stand some more rpm's. It made them live longer.<br /><br />Remember, you don't have to run it at WOT all the time. At lower throttle settings, it won't be working as hard.

 

[Jdeagro]

Re: OMC or AFTERMARKET Prop????

Boilermaker;<br /><br />Raise the engine!

 

[Jdeagro]

Re: OMC or AFTERMARKET Prop????

DHadley;<br /><br />Would like to talk to you,please call when you have ha momoment! 800-233-0194

 

[AUGIDAWG]

Re: OMC or AFTERMARKET Prop????

Hey Hooty,<br /><br />I've got my 95' Johnson revving 6000, and it sounds very happy, and doesn't sound like it is over reving by any means.<br />My question is, do you run your 200 for long periods, say, 30 minutes at 6200?<br /><br />I want to try and raise my engine, but I know the rpm will go up at least 200 rpm.<br /><br />Thanks.

 

[Hooty]

Re: OMC or AFTERMARKET Prop????

Hey AUGIDAWG,<br />I spin it 6200 as long as I can but not thirty minutes. Like Dhadley sez, I "run out of lake". As long as it's not over-heating, I'd run it like that for a full tank of fuel, which for my ole rag, is less then 20 min.<br />Run it like ya stole it.<br /><br />c/6<br />Hooty

 

[AUGIDAWG]

Re: OMC or AFTERMARKET Prop????

Well, my lake is the ocean, and if I had a big enough tank, I'd go to Japan and get some sushi!<br />Yuk,yuk.<br />We also have the San Francisco bay and delta<br />I have a 65 gallon tank with a range of something like over 120 miles at WOT.<br />It runs at 150 degrees at 6000 rpm, and the QL78YC plugs look great, light brown, no blisters, lots of oil on the threads.

 

[Dhadley]

Re: OMC or AFTERMARKET Prop????

nautiJohn --<br /><br />Getting ready to leave for a distributor show (Medart) in Lake Ozark. I'll be out the rest of this week but will call you when I get back. Or you can give me a shout at 800-321-1364 ext 3111 then.<br /><br />Unless youre gonna be at the show.......