Bass Tracker with 40HP Mariner Speed issues

[GrogHog]

Traybore can you snatch the prop and get a close up shot of the what most would call the back of the prop so we can see the curve or bend in it? This is going to be a great learning adventure for you as this prop will need to be rebuilt any way. You can always use it as a back up in case you loose the new one somewhere. I am going to be around my shop today so I can help with a few things for you. I will also check if I have an extra prop around her. I have a few 40s ? As I read yours is a 40 Mariner Is it a 4 cylinder and does it have 1 or 2 carbs ? What year? I will look through my records for the rite one for your boat.

 

[KRS62]

I have a 16ft Duracraft with a 50hp that is similar to your boat. With a 13p prop, it will get up to around 31-32 before I have to back off due to high RPMs. I just put a 15p on it, but have yet to test it. I am looking for little better cruise speed.

Your speed sounds way too low. How's the boat riding? Nose high? Nose low? I assume you have trim?

I wouldn't run that motor a second more with that prop.

KRS

 

[traybore]

It is a Mariner 40. I believe it is an 88 but not sure. It is a 2 cycle, 2 carb. I will try to post a close up of the prop when I get home from work this evening. Thanks for all the help guys!

 

[GrogHog]

Here is the 40 I have and it is on an 18' Monark pontoon. This boat will weigh twice yours is and will do nicely with 8 on board with all their gear. Fully loaded around 25 mph. the prop makes the difference. It is a SS Vengeance # 48-97868A 10 9p

Here is a link to a site I have used for years. This will help you on your quest and will be a good education tool. The more you find out about your equipment the safer and happier you will become.
Enjoy
Capt Rhan

https://boatpropellers.iboats.com/?cm_guid=1-_-100000000000001317031-_-12839768059&cm_mmc=Google_Main-_-Props%3AGoogle%3AFlorida-_-Boat+Propellers%3AProps%3AGoogle%3AFlorida-_-propellers_Phrase

 

[GrogHog]

Here are the photos of this prop and the link again to the prop site
https://boatpropellers.iboats.com/?cm_guid=1-_-100000000000001317031-_-12839768059&cm_mmc=Google_Main-_-Props%3AGoogle%3AFlorida-_-Boat+Propellers%3AProps%3AGoogle%3AFlorida-_-propellers_Phrase
Highlite this and drop into your browser

 

[traybore]

These are the worst two blades.

 

[chattahoochee]

Take a spinnerbait, bend the blade to look like your prop does, see how it performs.

Solas props from iboats are very reasonably priced AND if that is not the total problem you REALLY need a prop anyway.

 

[traybore]

Makes sense it would cause problems, just didn't know how much of a problem. Live and learn. After all the input from ya'll Im pretty convinced the prop is my main issue. The question now is whether to replace it with the same size, or something different. Im still less than $2k into the boat(including the boat, new decking, tuff coat, rod holders, seats, etc) so a couple hundred more to have it running as it should ain't gonna kill me. GrogHog, thank you for the link. Very informative.

 

[Loggerhead Mike]

My 17ft and 50hp run 32mph and jumps on plane quick as anything.

You said it ran fine "after" you got threw half tank of bad gas.

Did you run it out, then refuel with new?

What type of bass tracker do you have?

I ain't convinced its just your prop with that much of a performace loss.

 

[traybore]

16ft 1979 bass tracker. It had a couple gallons of bad gas(I guess). Mixed in some new so it would run, ran it dry, and filled back up with fresh, then ran it dry again. Im running it 50:1, from what I read that is the correct mixture. New plugs, removed/replaced the wet foam and rotten floors. Im sure the carbs still need a good cleaning as well. I checked the lower unit oil, no water. As far as I can tell the engine is fine aside from some minor adjustments. It will still die occasionally at idle, but since I dont have a tach on it, it may not be adjusted right. Im hoping that the prop is the major issue at the moment. I can keep fine tuning as I go on. It is power tilt only, no trim, so that may be off as well, dont really know how to check. It will get on a plane(kinda) but it doesnt want to, and only at WOT. Sometimes it will, sometimes it wont. If it doesnt, I can throttle down, and back up and then it will, or wont. I just repeat tell it starts getting up. Ive only had it on the water once so hopefully if the prop is off I didnt cause any permanent damage. Just learning as I go. Is there anything else you are thinking it may be? Thanks!

 

[traybore]

So I was unable to find what prop came on it originally. Went to Cabelas and the guy there looked up what they put on motors/boats of that size. Ended up with a 10 1/2 x 13P. Guess its a starting point. He said to test it out and if it didnt perform how I wanted to bring it back and they would exchange for another size until I got it right. Now to install a tach, and find time to make it to the lake...

 

[traybore]

Finally had a chance to test the new prop with a tach on the lake. As far as speed, I think it went slower with the new prop than the bent up one. Engine was at about 5100RPM at WOT. Im at a loss.

Just checked the compression. ~145 on one cyl, ~165 on the other. Not sure if that is good or bad. Also noticed the new plugs have black carbon build up on them. Running to rich?