atuck593
Well-known member
Long story short, the other day I was caught in a freak rain storm while out boating with my girlfriend. Saw it comming...tried to beat it back to the ramp...got soaked...girlfriend wasn't happy. I always check the weather before I go and it was one of those that just came out of nowhere. This event combined with the top speed thread that was posted lately have me trying to get more speed out of the 18 hp I am running. So far my top speed with 2 people has been 16 mph. I currently run a 68' Evinrude Fastwin on a 14' Starcraft Seafarer with added 1/2" carpeted floor and casting decks (you can see from photos on my build).
I have read on the top speed thread that people have been getting over 20mph with 2 people in loaded boats while running 15 - 20 hp motors. I have been trying to troubleshoot a few things from reading on this site and a few others and here is what I came up with.
1. Checked the spark plugs to make sure both cylinders are going. Minor carbon build up and same amount of carbon on each plug. Does this means that both are running and the same amount?
2. I did have the motor trimmed out to the second hole from the transom. I moved it to the third hole (but I haven't tested it out yet) would I be able to gain 5 - 6 mph from this move?
3. The cavitation plate is about 2.5" - 3" below the bottom of the hull. I know it should be even or a little higher than the bottom of the boat so I tried to raise the motor a little higher on the transom. I was able to split the difference and get it within 1.5" - 2" now, but it's still lower. How much speed would I gain if I installed a jackplate and pulled the cavitation plate even or a little higher than the bottom of the boat. Below is a picture of where the motor currently sits. I have taken off the whale tail because I read that it could slow the top end speed.
4. I have the stock prop that came with the boat. Not sure the pitch or width.
5. Would I be able to install a 20hp carb on this motor to increase hp? I read that the 18...20...and 25 hp from OMC all have interchangeable parts, but a 25hp carb would be too much for the 18. Would a 20hp carb bump it up a little?
I guess what I would like to know is, am I currently running as good as I will get with my setup? Is 16mph with two people good for my motor? I am assuming I can get a little over 20 by myself. How much more could I expect from my rig? I would love a newer 20hp 2 stroke but it's just not in the cards right now. As always any help, input, or advice would be great.
Thanks,
Alex
I have read on the top speed thread that people have been getting over 20mph with 2 people in loaded boats while running 15 - 20 hp motors. I have been trying to troubleshoot a few things from reading on this site and a few others and here is what I came up with.
1. Checked the spark plugs to make sure both cylinders are going. Minor carbon build up and same amount of carbon on each plug. Does this means that both are running and the same amount?
2. I did have the motor trimmed out to the second hole from the transom. I moved it to the third hole (but I haven't tested it out yet) would I be able to gain 5 - 6 mph from this move?
3. The cavitation plate is about 2.5" - 3" below the bottom of the hull. I know it should be even or a little higher than the bottom of the boat so I tried to raise the motor a little higher on the transom. I was able to split the difference and get it within 1.5" - 2" now, but it's still lower. How much speed would I gain if I installed a jackplate and pulled the cavitation plate even or a little higher than the bottom of the boat. Below is a picture of where the motor currently sits. I have taken off the whale tail because I read that it could slow the top end speed.
4. I have the stock prop that came with the boat. Not sure the pitch or width.
5. Would I be able to install a 20hp carb on this motor to increase hp? I read that the 18...20...and 25 hp from OMC all have interchangeable parts, but a 25hp carb would be too much for the 18. Would a 20hp carb bump it up a little?
I guess what I would like to know is, am I currently running as good as I will get with my setup? Is 16mph with two people good for my motor? I am assuming I can get a little over 20 by myself. How much more could I expect from my rig? I would love a newer 20hp 2 stroke but it's just not in the cards right now. As always any help, input, or advice would be great.
Thanks,
Alex