Starcraft SS 16 Mercury 85 HP

[Highwaystar]

Hello, i am new in this forum.
My name is dirk. I am from germany. I bought me a starcraft super sport 16 with a mercury thunderbolt 850 outboarder. Now i test the boat first time. The boat have 28 knots speed. I have no tachometer, but i think the rpm at wot are to high. There is a prop witch pitch 17, 3 blades. What props do you have for this boat? Many thanks for helping! Sorry my english is not good. Best regards Dirk

 

[Sea Rider]

Welcome to Iboats,

Without a tach OB is dead, that's the first thing you need to install. Then go for a wot run as usually loaded and check if OB runs ideally middle to max wot rpm factory stated for that OB. How many cylinders is that 850 ? Do you know the factory wot rpm range ?

Happy Boating

 

[Highwaystar]

Hi, the engine has 4 cylinders and wot rpm 5000-5500. Dirk

 

[Chris1956]

Dirk, We ran a 19P prop on a 16 foot fiberglass boat with that motor. You are probably correct that the motor is turning a bit too fast, of course without a tachometer, it is impossible to tell for sure..

 

[Watermann]

:welcome: to iboats Dirk, und viele gr??e aus Amerika!

You can look into a Tiny Tach for your boat motor and they are not very expensive.

There are many of us German Americans here and we love our Starcraft boats too! When you have time, post a foto of your boat here... http://forums.iboats.com/forum/owne...ts/345084-post-a-pic-of-your-starcraft/page95

There may be some members of the Starcraft forum that have the exact same boat and motor who can help as well.

 

[Highwaystar]

Thank you gor Information! Dirk

 

[jimmbo]

A 17 in prop on a 4 cylinder 850 would give a speed range of about 30mph to 34mph allowing for about 13% slip. A 17 on that boat is probably pretty close

 

[82rude]

I use a 17 p prop generally for my 1976 ss 160 .2011 60hp etec.

 

[82rude]

Should of mentioned by gps 32 to 33.9 mph.I would venture your 85 if healthy should get 37 or so .I would try a 19p.possibly 17 depending on the gear ratio in lower unit.

 

[Highwaystar]

I think i buy me a 19 Prop and a Tachometer. Then i will test it. Thank you all for the Tipps Regards Dirk S?ssmann, Seligenstadt, Germany

 

[Texasmark]

I ran the 850 4 cyl on a 16' Fiberglass Falcon with a stepped transom....transom area was flat but the center section was still flat but a couple inches deeper than the outer parts making a "PAD" of sorts. Prop was a Merc 19P Laser and ran 38 (instruments) running alone. The boat was long and narrow and there wasn't much of it in the water after trim corrections. I don't remember my tach readings however....why not that and all the rest? Don't know. I was looking for speed at the time and didn't pay that much attention to where the rpms were running....that was back in 1974 time frame and I hadn't become a member of iboats learning what I didn't know back then through the association and on my own with current equipment. Ha!

 

[walleyehed]

Put a Tachometer in/on...test. If it's not over 6000rpm, I wouldn't touch a thing. If it IS over 6000, look into a new 17P prop first. Nobody can know with that vintage if it even has a prop with any late technology in it. You may have an old, un-cupped prop, who knows? 1 thing at a time or you'll never know what fixed what or where to go next.

 

[Texasmark]

Put a Tachometer in/on...test. If it's not over 6000rpm, I wouldn't touch a thing. If it IS over 6000, look into a new 17P prop first. Nobody can know with that vintage if it even has a prop with any late technology in it. You may have an old, un-cupped prop, who knows? 1 thing at a time or you'll never know what fixed what or where to go next.

Welcome back stranger!

 

[walleyehed]

Hello sir!!! Thought I best come see if you was keepin' everyone in line here.. Looks like you've got things well under control!!

 

[Texasmark]

Hello sir!!! Thought I best come see if you was keepin' everyone in line here.. Looks like you've got things well under control!!

Trying harder to behave myself so the site cops won't kick me off......grin.

 

[jbcurt00]

Its been about 6wks since the OP posted here, how about we let him post to re-up the topic......

 

[Texasmark]

I guess I'm as guilty as anybody. I normally pay attention to the date of the last post, not the actual date since I have to pull it up and deliberately check the date of origin. Sorry about that. Your point is well taken. Seems if here were that interested in our following, he would have kept in touch.

 

[Highwaystar]

Put a Tachometer in/on...test. If it's not over 6000rpm, I wouldn't touch a thing. If it IS over 6000, look into a new 17P prop first. Nobody can know with that vintage if it even has a prop with any late technology in it. You may have an old, un-cupped prop, who knows? 1 thing at a time or you'll never know what fixed what or where to go next.

Now I have an 19 pitch Prop, and this is not OK. I think your Tip a new 17 Prop is well!