[frers-list]Propeller Sizing
Jerry Black
frers-list@lists.frers33.com
Thu, 26 Mar 2020 17:02:35 +0000 (UTC)
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I have a 2 bladed max-prop feathering. =C2=A06 kts at 2,000rpm. Best thing =
is that when backing down you get the same thrust since the bldes rotate 18=
0 deg. Also I don't have to align the shaft to insure folding. My preferred=
option if I have to replace.
Jerry BlackPelirrojas
-----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
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#yiv2337709264 div.yiv2337709264WordSection1 {} -->When running at 2900R=
PM (race clean & prepped bottom) in pretty flat (<1ft seas) water and light=
wind, I'm usually doing about 5.2-5.4kts, where it seems like I should be =
doing at least 6kts at that RPM.=C2=A0 Further I=E2=80=99ve never found whe=
re the throttle actually stops because it reaches max RPM before it runs ou=
t of power (also suggesting not enough propeller). =C2=A0 My prop is the s=
ame Martec 16x10 two blade folding prop that at least a couple other boats =
have (I definitely spied on a few of your props in the boatyard recently=F0=
=9F=98=88).=C2=A0 Does anyone have experience going to a higher pitch, some=
thing like a 12=E2=80=9D opposed to the 10=E2=80=9D?=C2=A0 Some generic cal=
culations I looked up suggested a 13=E2=80=9D, and =C2=A0Gary from Martec s=
aid he too thought 10 was underpitched for the boat but suggested 12 as pro=
bably the right pitch.=C2=A0 Before I send the prop off (it=E2=80=99s alrea=
dy removed for the cutlass bearing replacement), I wanted to check and see =
if anyone has done testing and played with repitching the prop. =C2=A0 Sent=
from Mail for Windows 10 =C2=A0=20
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<div style=3D"color:black;font: 10pt arial;">I have a 2 bladed max-prop fea=
thering. 6 kts at 2,000rpm. Best thing is that when backing down you =
get the same thrust since the bldes rotate 180 deg. Also I don't have to al=
ign 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">-----=
Original 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">
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<style><!-- #yiv2337709264 _filtered {} _filtered {} #yiv2337709264 =
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<div class=3D"yiv2337709264WordSection1">
<div class=3D"yiv2337709264MsoNormal">When running at 2900RPM (race clean &=
amp; prepped bottom) in pretty flat (<1ft seas) water and light wind, I'=
m usually doing about 5.2-5.4kts, where it seems like I should be doing at =
least 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 =
of 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 =
blade folding prop that at least a couple other boats have (I definitely sp=
ied on a few of your props in the boatyard recently
<span style=3D"font-family:UI sans-serif;">=F0=9F=98=88</span>). Does=
anyone have experience going to a higher pitch, 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 said he too thought
10 was underpitched for the boat but suggested 12 as probably the right pi=
tch. Before I send the prop off (it=E2=80=99s already removed for the=
cutlass bearing replacement), I wanted to check and see if anyone has done=
testing and played with repitching the prop.</div>
<div class=3D"yiv2337709264MsoNormal"> </div>
=20
<div class=3D"yiv2337709264MsoNormal">Sent from <a rel=3D"noopener noreferr=
er" target=3D"_blank" href=3D"https://go.microsoft.com/fwlink/?LinkId=3D550=
986">
Mail</a> for Windows 10</div>
<div class=3D"yiv2337709264MsoNormal"> </div>
=20
</div>
</div>
</div>
</div>
</div>
</div>
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