1985 90 hp Merc Prop

[mnmfors]

Hello everyone,<br /><br />This engine is mounted on a 1968 19' 3" Cobia boat with a Cabin. (1986 90 HP Merc). However I have not been able to get it running yet. I am saving up for a trigger.<br /><br />I spun the hub out of my previous 14 x 19 SS cupped. (Engine was on a 17 ft bass boat and propped correct) <br /><br />I also have a 15 x 22 Chopper, that I could sell or trade for the right prop, but I really wanted to keep it. (I don't know why)<br /><br />Should I go ahead and have the 14 x 19 rehubbed, or sell/trade chopper prop for another pitch?

 

[LubeDude]

Re: 1985 90 hp Merc Prop

This is a top of my head response, as Im just shooting from the hip on this one, but might be of some help!<br /><br />First of all I personally think this setup it going to be under powered! You will probably have to run at WOT most of the time and this is going to be hard on fuel economy! Secondly I think that you are going to have to go with at least a 17 Pitch if not a 15 to get this boat on plane decently! Find a marine dealer that will work with you on the prop, some will let you try props with a deposit!<br /><br />Ive sold props on Ebay and they usually do pretty good if you do not want new prices for them!<br /><br />LubeDude

 

[mnmfors]

Re: 1985 90 hp Merc Prop

Thanks for the reply Lube Dude,<br /><br />I want to add that I had a Johnson V-4 115 hp with an alluminum 19 pitch. Even with a burnt piston, it planed nicely. (it took a while to build compression in the burnt up cyl.) <br /><br />My experience with this 90hp merc has been that it actually is more like a 115 hp. For example, my friend had a 115 Yamaha mounted on a 15ft glassstream, and my 90 was on a 17ft Glasstream. We were both running 19" SS props. I had a better hole shot, and I pulled away from him at top end. Although in fairness, my friend never did maintenance (plugs, decarb, etc.)<br /><br />I was looking through my manual last night, and I could not find the difference between a 90hp and a 115hp. Just the WOT is 4500-5000 on the 90 and 5000-5500 on the 115. (I have a 115 lower unit on it which I believe is the same 2:1 ratio)<br /><br />I know that I won't ever get the speed and hole shot I got with the bass boat. I just want a boat to go to the island and do a little camping etc. I was hoping to get 35mph+. I do hope I can pull a tube or a skier/kneeboarder this coming spring/summer. I really like the boat because it is stable, safe, and practical for a family of 5.<br /><br />Thanks in advance for any replies.