2006 75hp optimax on a 16.5 lund angler

[yellowbelly]

picked up this motor cause of the deal i got, it came with a 19p stainless 3 blade prop... i took it for a test run today and im getting 3700 rpms and moving @38mph loaded with gear and 10gallons of fuel..i mounted the motor so the cav plate is 1/4" about the bottom of the boat..i also have a 17p alum. prop will this help in my rpm's get closer to 5000-5500 recommended wot range

 

[Bondo]

picked up this motor cause of the deal i got, it came with a 19p stainless 3 blade prop... i took it for a test run today and im getting 3700 rpms and moving @38mph loaded with gear and 10gallons of fuel..i mounted the motor so the cav plate is 1/4" about the bottom of the boat..i also have a 17p alum. prop will this help in my rpm's get closer to 5000-5500 recommended wot range

Ayuh,.... Try it, it's bound to Help,..... though it sounds like there's other issues,...

Was the motor trimmed, 'n runnin' right,..??

Is the Tach readin' right,..??

 

[steelespike]

I think your tach or speedometer are whacky. 38 mph is in the ball park,My info indicates 38 requires 5700 rpm. with a 19" prop and your 2.38 gear ratio.
Is your speed by gps.

 

[SkiDad]

i agree - tach seems way off.

 

[yellowbelly]

speed is off a Lowrance hds12 graph/gps unit. motor was trimmed up to the point where the stern of the boat felt like it was in ice..the tach is still at the setting for my 40hp efi 4 stroke motor.. at idle the rpms are spot on..im not 100% what setting the opti is suppose to be set to my service guide does not state that..motor runs perfect.. the motor does not sound like its running at 5700 rpms

 

[SkiDad]

if my calculations are correct 3700 with old tach settings would translate to 5550 on new. If you get your tach set for the right number it should solve that.

i did 3700 * 3 / 2 - 3 hits on new engine vs 2 on old (b/c it's a 4 stroke)

 

[yellowbelly]

gonna head down to the boat here in a bit will post a update

 

[steelespike]

Your speed should be accurate. If we use a 19" prop,2.30 gear ratio,estimate 12% slip,we get 5500 rpm.If we use a 2.38 ratio we get 5700.

 

[yellowbelly]

ran down and put the 17p alum mercury prop on with the setting on the tach where it was at im at 4100rpms and 38mph going down river..the stainless 19p was 41mph down river..i changed the tach setting to what i thought might me right and it was 6k wot with no alarms? so that cant be right...im gonna order the smartcraft gauge tomorrow and be done with it... this is at idle

 

[steelespike]

What is the down river current?
How is the overall performance with the 19? From the few tests it seems that normally a typical prop would be a 17 or lerss.

 

[yellowbelly]

the current is 1.5-2mph give or take a little with wind...the 19p was tough to control the boat pulled bad and going by ear the motor wasn't working that hard..the 17p was easier to handle and it performed just as well just not as fast..i really need to find out what setting this tach is suppose to be at,i cant find nothing on the internet about that

 

[yellowbelly]

update..called mercury they gave me the info about the tach setting, ran down set it to 6p started the motor and calibrated to the idle rpms motor is set to idle at 650 so that's where i set it to.. out on the water wot is 5400 now at 39mphwith the alum. 17p prop ..if i trim it up too much i get a beep so im assuming low water pressure or getting close to the max rpm range..ill put the 19p prop on next week and see what rpm's are and go from there..mercury customer service was great no holding for a tech...so is that about all im gonna get out of a 75hp motor on a 16' boat?

 

[Silvertip]

That boat with that engine should do over 40 mph and closer to 45 with a light load and a 19p Quicksilver prop. I speak from experience.

 

[steelespike]

According to my info the 2006 Angler 165 is 17' and dry weight is 1070 lbs.I bet your about 2000 all up.
On top of that some Aluminum boats though relatively light can be hard to push.
I think 39 is respectable if you consider a 18ft 3.0 I/O about 135 hp makes around 40.