Propellor Modification Mariner 15hp

[werdna]

Hi all,<br />I have just had my prop 'serviced' when i got the bush replaced. The guy at the prop shop suggested that he turn the flange off the prop if i wanted more power/speed out of my motor. He turned the majority of the flange off, down to about 2-3mm from the shaft. Just wondering if this will actually increase power/speed, as i have been having lots of problems with it cavitating and a severe lack of power under load. Any suggestions are welcomed. It seems to me that its revving faster than we are actually moving. It is a 'power prop' on a 4m open dinghy, but its not even been getting up on to the plane with 3 POB and it was put on a pitch block when it was serviced, but i was told the pitch was perfect.<br />Cheers Andrew

 

[The Marine Doctor]

Re: Propellor Modification Mariner 15hp

This may not be a problem with your engine or your prop. Some design changes have come into effect with inflatables in recent years to get them up on plane better with lower HP engines.<br /><br />If you check out the new Mercury inflatable boats you will see what I mean.<br /><br />TMD

 

[The Marine Doctor]

Re: Propellor Modification Mariner 15hp

This may not be a problem with your engine or your prop. Some design changes have come into effect with inflatables in recent years to get them up on plane better with lower HP engines.<br /><br />If you check out the new Mercury inflatable boats you will see what I mean.<br /><br />TMD

 

[werdna]

Re: Propellor Modification Mariner 15hp

TMD,<br />Sorry i probably didnt make my case out too well. Ive been running the motor on the boat for one year now and have only just had the prop serviced.<br /><br />

<br /><br />Basically I'm just wondering if the removal of the flange could cause any difference in the performance of the prop, especially this cavitation thing.<br />Cheers,<br />Andrew<br /><br />Edit: lowered the res of the pic

 

[werdna]

Re: Propellor Modification Mariner 15hp

Any ideas please? I'm thinking about letting the prop guy know my case tomorrow, so any ideas would be great. Anyway, im off to bed now.<br />Cheers Again,<br />Andrew

 

[The Marine Doctor]

Re: Propellor Modification Mariner 15hp

The prop will work better with the Diffuser ring. I believe it is there so that the exhaust does not feed back into the prop.<br /><br />TMD

 

[Spidybot]

Re: Propellor Modification Mariner 15hp

Werdna,<br /><br />feel free to check my homepage for a booklet on props.<br /><br />PS! Did you put up your pic in very-high-resolution? It takes a zillion to download it.....

 

[werdna]

Re: Propellor Modification Mariner 15hp

Many thanks UU and TMD. Sorry about the pic - its a high res + its coming off my own server which is just connected via a 512/128kb ADSL. Cheers for the advice and i'm on my way to your website UU.<br />Cheerio<br />Andrew

 

[werdna]

Re: Propellor Modification Mariner 15hp

Heres a pic of the prop, with the diffuser ring (or lack thereof). Any opinions?<br />

<br />(the res of this one is a little smaller )

 

[werdna]

Re: Propellor Modification Mariner 15hp

Any suggestions? looks like it's back to the prop shop tomorrow. Please let me know your opinion, it would be much appreciated.<br />Cheerio<br />Andrew