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Old 30 July 2007, 19:39   #11
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props

u should have a spare set of props i carry 2 spare stainless props and pins + nuts if i only had 1 engine i would defo have a spare aux outboard 3-5hp
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Old 30 July 2007, 19:45   #12
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Well its not much dearer than an ally prop , and 19" which is what I have now (good for cruising) thought maybe it was a good bet and if the performance was better with stainless , I dunno maybe cos its thinner or sharper etc , then could go somewhere towards my 18" pitch ideal.

I thought the rubber bushed hub was supposed to fail before the shaft or gearbag got damaged .

i guess the old shearpin had its advantages .
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Old 30 July 2007, 19:52   #13
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all i can say is if u want this prop get it but if you do hit anything it will hust (your pocket)

all the best guys if you want a ride on the boat if ur in cardiff pm me

ryan
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Old 30 July 2007, 19:53   #14
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that was ment to say hurt
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Old 30 July 2007, 20:13   #15
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Hi Ian,
Just looking at your above post & you say your pushing a 19" alloy prop with a Suzi DF70 on a 4.7ish boat.....what are your rev's at WOT? Im running a 14" stainless with a Yam 60 on a 4.8 boat & not hitting top revs but i get v-good all round performance, i can only get to top rev's with an alloy 14" but that gives me poor 'out of the hole' performance but great top end, good if the sea is mirror flat but crap in a big sea. Just sounds to me like your well over proped on your boat currently......i could be wrong though but it would be interesting to know what revs your pulling WOT & your current top speed before you puchace the new prop.
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Old 31 July 2007, 02:18   #16
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Quote:
Originally Posted by ian parkes View Post
i guess the old shearpin had its advantages .

Yep and there was normally a spare under the cowl
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Old 31 July 2007, 05:49   #17
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Hi Ian,
Just looking at your above post & you say your pushing a 19" alloy prop with a Suzi DF70 on a 4.7ish boat.....what are your rev's at WOT? Im running a 14" stainless with a Yam 60 on a 4.8 boat & not hitting top revs but i get v-good all round performance, i can only get to top rev's with an alloy 14" but that gives me poor 'out of the hole' performance but great top end, good if the sea is mirror flat but crap in a big sea. Just sounds to me like your well over proped on your boat currently......i could be wrong though but it would be interesting to know what revs your pulling WOT & your current top speed before you puchace the new prop.
This prop science seems to vary a lot . My max recomended rpm is 5800
The boat came with a 17" pitch fitted . With that prop it would pull 5800 at 36mph loaded with 3 people full fuel etc but it was a bit lively with less load and tended to over rev a little .

I then fitted a 19" pitch which gave more relaxed cruise but would only pull 34 mph at about 5300 rpm same load .

From that I figured an 18" pitch would be ideal ,but an 18" isn't available . Iam now waiting to try the original 17" prop which I has been re pitched to 18

My thoughts with the stainless 19" that is on offer were that if stainless gave better performance it may just do the job allround and I would also have a spare prop or two. Its just expensive trial and error it seems .
Not sure what dia your prop is mine is 13 1/4 " maybe thats the difference .
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Old 31 July 2007, 05:50   #18
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Hi Ian,
Just looking at your above post & you say your pushing a 19" alloy prop with a Suzi DF70 on a 4.7ish boat.....what are your rev's at WOT? Im running a 14" stainless with a Yam 60 on a 4.8 boat & not hitting top revs but i get v-good all round performance, i can only get to top rev's with an alloy 14" but that gives me poor 'out of the hole' performance but great top end, good if the sea is mirror flat but crap in a big sea. Just sounds to me like your well over proped on your boat currently......i could be wrong though but it would be interesting to know what revs your pulling WOT & your current top speed before you puchace the new prop.
This prop science seems to vary a lot . My max recomended rpm is 5800
The boat came with a 17" pitch fitted . With that prop it would pull 5800 at 36mph loaded with 3 people full fuel etc but it was a bit lively with less load and tended to over rev a little .

I then fitted a 19" pitch which gave more relaxed cruise but would only pull 34 mph at about 5300 rpm same load .

From that I figured an 18" pitch would be ideal ,but an 18" isn't available . Iam now waiting to try the original 17" prop which has been re pitched to 18

My thoughts with the stainless 19" that is on offer were that if stainless gave better performance it may just do the job allround and I would also have a spare prop or two. Its just expensive trial and error it seems .
Not sure what dia your prop is mine is 13 1/4 " maybe thats the difference .
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Old 31 July 2007, 05:53   #19
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sorry posted twice don't know how that happened , had to re log twice ?
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Old 31 July 2007, 06:52   #20
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Hi Ian,
Rule of thum is you go down one pitch to achive the same performance when going from alloy to stainless the difference is the stainless prop is probably cupped & definetly has thinner blades so will load up a lot better thus giving a lot better performance with no slip (you could also try lifting your engine one bolt hole to gain better top end), If you go for a four blade then it will also give you better 'bow lift' & hold you on the plane at slower speeds. Also forget the max RPM what you need to know is at what rev's you get max BHP this will lower than your max rev's & this is where you want to be when you have a loaded boat. Personally if i where you i would go for a 17" four blade prop from Steel Developments they will alter the pitch up or down for you that way you should gain back some of your top end but still gain benifits lower down the rev range as well, should be better on fuel than 19" too as IMHO the engine will labour to much trying to turn a 19" prop in any sea state other than mirror flat.
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