prop questions

[nzer]

gday. i have a light, open 16 foot aluminium boat with a 1992 yamaha 40hp outboard. it goes ok but is slow off the mark and has little top speed. the prop on the motor is pretty buggered and i would like to replace it. i am not able to get the numbers off the prop at present as the boat is not handy and i am surfing the net but can anyone give me some clues as to what a good prop selection would be? i use the boat primarily for river work and also some scallop dredging. if it would help i can get the numbers off the current prop but it is that rooted it wouldn't be fair to say that particular prop is no good. cheers for any help offered.

 

[stevens]

Re: prop questions

That's probably not enough information for the guys to give you an exact recommendation.<br /><br />Now, if you had the pitch and diameter of your current prop, that would be a good starting point.<br /><br />If the numbers on it are impossible to read, there was this thread here earlier that showed how to easily estimate the pitch yourself: iboats thread

 

[Silvertip]

Re: prop questions

Go to Yamaha's marine web site and look at Performance Tests. You can select the engine, boat type, model year(s) and performance data are shown for the boats you've selected. Although the exact boat as yours may not be listed, one similar in design, weight, and length will be shown. They always list the prop part number, diameter, and pitch used in the test. Your engine as I remember has a 1.85:1 lower unit ratio which I'm guessing would probably use a 12 or 13 pitch prop on a boat such as yours.

 

[nzer]

Re: prop questions

i had a look at the yammy website but can't really compare those boats to what i've got without seeing them. my boat is called a "fyran" and is basically a 16 foot, medium v, open dinghy. heres a link if you want to see it http://www.fyran.co.nz/frames.html. i had a look at the old prop and from what i can make out it is a 11 3/8 -12g. the edges of this prop are frayed and very thin so a new one of the same could be ok. i bought the motor second hand about 4 years ago and have been making do but was just wondering if anyone here had any better ideas. cheers for the replys so far.

 

[nzer]

Re: prop questions

i just had a llok at the link and it doesn't work. if you want to see it try this link http://www.fyran.co.nz and go to the classic 16 xt.