Props between sizes

[ian parkes]

With the 13x17 prop that my boat came with I felt it was just a little underpropped .
It peaked at 5900 at about 36mph even well loaded and was very responsive to the throttle . I think 5800 is max rpm

I have fitted a 19 pitch prop and with same full fuel load but only one passenger it was great peak revs at 5500 and 39mph and more relaxed cruising.

At the weekend I went out with 3 people on board and a bit more gear it still felt the same easy cruising up to 30 mph which was enough in the chop. when I found some calmer water I tried WOT but it wouldn't rev much past 5000 and only did 33mph .

is it worth looking for a prop between the two or is this a pretty normal situation .
Iam not so worried about top speed , more relaxed aconomical cruising is better. i havent had a chance to compare fuel consumption yet to the old prop but I feel if the engine is labouring a little it may not be as good .

Both props are like new and alloy suzuki items .

[simmons0]

Can ally props be altered in the same way stainless ones can?

If it was a stainless prop i'd say take it to SteelDev's or Prop revolutions and ask them to decrease the pitch an inch. Probably they can do the same with Ally ones.

Harry

[ian parkes]

Thats what iam thinking of doing , just don't want to waste money if its a waste of time .

[toby4594]

Alloy props can be according to steel devs altered by 2" of pitch where as stainless by 1" only.

[sticky]

Originally Posted by ian parkes

Thats what iam thinking of doing , just don't want to waste money if its a waste of time .

Hi Ian long time no see, came accross this product,solve all your probs, you could change at will + you get a garantee exchange if not right.
http://www.piranha.com/
Seems a very clever concept "if it works"
Theres actually a dealer near you.
Give are best to family.

[Nos4r2]

I found its a hard decision what to do with prop sizes when the boat gets split solo/2+passengers usage. I've got 2 props for that reason. It doesn't take long to change one.

[ian parkes]

sorry for disapearing
My pooter died and I just got it back .

Hi Sticky Ill have a read about that piranha prop system thanks

As you say Nos its easy to change the prop so Ill live with that for now athe 19 pitch pulls ok just loss of top speed when loaded but that goes for any boat I guess its just more noticable with a smaller boat .

[ADS]

I would keep both and buy one of those floating prop wrenches. Incidently I was quoted £35 to alter the pitch of an alloy prop, although if you alter the 19" you will be back where you started....

[ian parkes]

Originally Posted by ADS

I would keep both and buy one of those floating prop wrenches. Incidently I was quoted £35 to alter the pitch of an alloy prop, although if you alter the 19" you will be back where you started....

Floating prop wrench is probably a good idea ,although I hope not to change the prop while afloat .
its the split pin thats the pain I find stainless ones are harder and snap off so a new one is needed every time and currently I can only find a little pack of 3 at the chandlers for about £3.
does anyone use any sort of reusable pin like an R clip or snap ring pin. I have some but was worried that it may cause problems in some way??

[sparkey]

does anyone use any sort of reusable pin like an R clip or snap ring pin. I have some but was worried that it may cause problems in some way?? [/QUOTE]

would not recomend R Clip because
(1) could be removed if caught on rope or in sea weed.
(2) Centrifugal action with prop rotating @ 4000 rpm could dislodge R clip causing nut to open and loss of prop.

I had a 1.7 merc diesel engine on my last boat. Removed it after 1 season ( aprox 75 hrs) diesel problems and cooling problems , dealer could not sort despite many visits. Would not even use it as a weight for a swing mooring.