[frers-list]Propeller Sizing
Art Kelley
frers-list@lists.frers33.com
Thu, 26 Mar 2020 14:57:01 -0400
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16x10 was the original prop. Somewhere in our archives there was a descripti=
on of someone going to a longer blade, says there is room for that.=20
I fixed the problem I had last year when I couldn=E2=80=99t get full speed f=
rom my engine. The throttle cable finally snapped and when I put the new one=
on, I found the revs I had lost over the years. I am back to getting 3600-=
3800 ROM. Much cheaper than a new prop.=20
Art
> On Mar 26, 2020, at 1:02 PM, Jerry Black <jcblack099@aol.com> wrote:
>=20
> =EF=BB=BF
> I have a 2 bladed max-prop feathering. 6 kts at 2,000rpm. Best thing is t=
hat when backing down you get the same thrust since the bldes rotate 180 deg=
. Also I don't have to align the shaft to insure folding. My preferred optio=
n if I have to replace.
>=20
> Jerry Black
> Pelirrojas
>=20
>=20
> -----Original Message-----
> From: Brian Higgins <brian@sailingit.com>
> To: frers-list@lists.frers33.com <frers-list@lists.frers33.com>
> Sent: Thu, Mar 26, 2020 11:42 am
> Subject: [frers-list]Propeller Sizing
>=20
> When running at 2900RPM (race clean & prepped bottom) in pretty flat (<1ft=
seas) water and light wind, I'm usually doing about 5.2-5.4kts, where it se=
ems like I should be doing at least 6kts at that RPM. Further I=E2=80=99ve n=
ever found where the throttle actually stops because it reaches max RPM befo=
re it runs out of power (also suggesting not enough propeller).
> =20
> My prop is the same Martec 16x10 two blade folding prop that at least a co=
uple other boats have (I definitely spied on a few of your props in the boat=
yard recently =F0=9F=98=88). Does anyone have experience going to a higher p=
itch, something like a 12=E2=80=9D opposed to the 10=E2=80=9D? Some generic=
calculations I looked up suggested a 13=E2=80=9D, and Gary from Martec sai=
d he too thought 10 was underpitched for the boat but suggested 12 as probab=
ly the right pitch. Before I send the prop off (it=E2=80=99s already remove=
d for the cutlass bearing replacement), I wanted to check and see if anyone h=
as done testing and played with repitching the prop.
> =20
> Sent from Mail for Windows 10
> =20
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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto">16x10 was the original prop. Somewhere in o=
ur archives there was a description of someone going to a longer blade, says=
there is room for that. <div><br></div><div>I fixed the problem I had l=
ast year when I couldn=E2=80=99t get full speed from my engine. The throttle=
cable finally snapped and when I put the new one on, I found the revs I had=
lost over the years. I am back to getting 3600-3800 ROM. Much c=
heaper than a new prop. <br><br><div dir=3D"ltr">Art</div><div dir=3D"l=
tr"><br><blockquote type=3D"cite">On Mar 26, 2020, at 1:02 PM, Jerry Black &=
lt;jcblack099@aol.com> wrote:<br><br></blockquote></div><blockquote type=3D=
"cite"><div dir=3D"ltr">=EF=BB=BF
<div style=3D"color:black;font: 10pt arial;">I have a 2 bladed max-prop feat=
hering. 6 kts at 2,000rpm. Best thing is that when backing down you ge=
t the same thrust since the bldes rotate 180 deg. Also I don't have to align=
the shaft to insure folding. My preferred option if I have to replace.
<div><br>
</div>
<div>Jerry Black</div>
<div>Pelirrojas<br>
<br>
<br>
<div style=3D"font-family:helvetica,arial;font-size:10pt;color:black">-----O=
riginal Message-----<br>
From: Brian Higgins <brian@sailingit.com><br>
To: frers-list@lists.frers33.com <frers-list@lists.frers33.com><br>
Sent: Thu, Mar 26, 2020 11:42 am<br>
Subject: [frers-list]Propeller Sizing<br>
<br>
<div id=3D"yiv2337709264">
=20
=20
<style><!-- #yiv2337709264 _filtered {} _filtered {} #yiv2337709264 =
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<div>
<div class=3D"yiv2337709264WordSection1">
<div class=3D"yiv2337709264MsoNormal">When running at 2900RPM (race clean &a=
mp; prepped bottom) in pretty flat (<1ft seas) water and light wind, I'm u=
sually doing about 5.2-5.4kts, where it seems like I should be doing at leas=
t 6kts at that RPM. Further I=E2=80=99ve never found where
the throttle actually stops because it reaches max RPM before it runs out o=
f power (also suggesting not enough propeller).</div>
=20
<div class=3D"yiv2337709264MsoNormal"> </div>
=20
<div class=3D"yiv2337709264MsoNormal">My prop is the same Martec 16x10 two b=
lade folding prop that at least a couple other boats have (I definitely spie=
d on a few of your props in the boatyard recently
<span style=3D"font-family:UI sans-serif;">=F0=9F=98=88</span>). Does a=
nyone have experience going to a higher pitch, something like a 12=E2=80=9D o=
pposed to the 10=E2=80=9D? Some generic calculations I looked up sugge=
sted a 13=E2=80=9D, and Gary from Martec said he too thought
10 was underpitched for the boat but suggested 12 as probably the right pit=
ch. Before I send the prop off (it=E2=80=99s already removed for the c=
utlass bearing replacement), I wanted to check and see if anyone has done te=
sting and played with repitching the prop.</div>
<div class=3D"yiv2337709264MsoNormal"> </div>
=20
<div class=3D"yiv2337709264MsoNormal">Sent from <a rel=3D"noopener noreferre=
r" target=3D"_blank" href=3D"https://go.microsoft.com/fwlink/?LinkId=3D55098=
6">
Mail</a> for Windows 10</div>
<div class=3D"yiv2337709264MsoNormal"> </div>
=20
</div>
</div>
</div>
</div>
</div>
</div>
</div></blockquote></div></body></html>=
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