Avon 620 open adventurer Yamaha F115 4 stroke

[Prattyboy]

Bought this bought about a month ago and loving it with the family. The only thing is when I 1st bought it it would do about 33 mph at WOT (5000rpm). A month on it is only doing about 25 mph. It is moored at a marina and there's a little growth on the hull...but would this make a real difference? The engine is 2007 still under warranty and sounds and runs fine. it has a standard 17" prop. Would going to a slightly larger prop make that much difference / damage the engine?

Cheers for any thoughts.

Prattyboy

[PeterM]

I think that a months growth in the recent warmish weather is your problem. Try taking it out of the water , clean it & then see if you get the MPH back .

[Chris]

2 weeks in a marina saw me loose 3 knots.

[Prattyboy]

thanks for replies. Growth looks like it's fairly well advanced so will take out this weekend. Apart from pressure hose cleaning is there any solution you can recommend?

[PeterM]

I find just elbow grease & a light green scouring type pad - take the growth off without scratching the gel.

[codprawn]

Originally Posted by Blackroady

I find just elbow grease & a light green scouring type pad - take the growth off without scratching the gel.

I agree - unless you have barnacles and then you need a plastic windscreen scraper.

[PeterM]

Originally Posted by codprawn

I agree - unless you have barnacles and then you need a plastic windscreen scraper.

Good point - mine live in fresh water , apart form the odd few days here & there - so never really seemed to affect me . Do barnacles even live in fresh water ? Never occured to me before !

[codprawn]

Originally Posted by Blackroady

Good point - mine live in fresh water , apart form the odd few days here & there - so never really seemed to affect me . Do barnacles even live in fresh water ? Never occured to me before !

No and it's a good way to remove them - stick the boat in fresh and it kills them off - doubt it will remove the rings they leave behind though - you need acid for that!!!

[mikesyam]

My Humber needs a clean speed down from 52mph to 42mph, makes a big difference but in lazy mode at the minute.

[walruz]

I use concentrated hydrochloric acid from a garening type spray can. Just spray it on leave 5 mins and wipe off with a deck scrubber. Reapply on the odd patch that didn't completely wipe off.

It is used on all the quays around the islands as well as it doesn't do any damage to the envirnment.

ian