Do any C275 owners think the boat comes underpropped?
From what I understand (I’m no expert but learning fast) a 5000lb 26’5” LWL D/L Ratio=121 monohull driven by a 14hp sail-drive should under power readily achieve hull speed. Mine doesn’t. On a glass calm day its Yanmar 2YM15 stretches all the way out to 3800rpm governor cut-off achieving only 6.3-6.4 knots through the water. In any case the set-up doesn’t quite ‘feel’ to have the right amount of bite relative to work-rate… I’m underpropped.
My boat came with a folding 2 blade 15/10 fixed, in place of (what I believe to be standard Catalina factory release) fixed 2 blade 14/11. At first I assumed the lesser pitch on the replacement folder was the issue. Due to potential long term issues associated with underworking the diesel / not wanting to ever be caught on a lee shore in a blow without enough drive to effectively get off / and just wanting to charge around the harbour more efficiently - I’m now looking into getting this sorted.
I definitely want to stick with a folder, but don’t have budget for an outright replacement folder/feathered. So I’m looking to replace blades on the existing Volvo stock during annual haul out this coming southern Spring.
In discussion with a diesel mechanic prop supplier, he explained a 15/10 should give at least a like performance to a 14/11 on basis the extra open blade diameter should make up for its lesser pitch (that opinion subsequently backed up by a 2nd prop supplier) so he was a bit surprised. I then sent him the attached data sheet for the boat, his thoughts are the boat might come out of the factory a bit underpropped on basis a 2YM15 shouldn’t quite rev to 3670rpms with the right amount of prop resistance. He suggested going for a bit of increased pitch - above 14/11 - to ensure I get a noticeable improvement and to justify the exercise.
To keep this economical I want to get replacement blades that achieve a result however at the same time without over-propping (and potentially setting myself up for long term issues in that direction). So I want to try and get this right first pass, done during ant-fouling and back in the water same day - without any follow up haul out remedial buggeration.
To that end... I’m curious to know from any other C275 owners (those with inboard auxiliary & saildrive):
What is your prop diameter/pitch? Are you getting 6.9-7.0 knots with it?
Cheers
From what I understand (I’m no expert but learning fast) a 5000lb 26’5” LWL D/L Ratio=121 monohull driven by a 14hp sail-drive should under power readily achieve hull speed. Mine doesn’t. On a glass calm day its Yanmar 2YM15 stretches all the way out to 3800rpm governor cut-off achieving only 6.3-6.4 knots through the water. In any case the set-up doesn’t quite ‘feel’ to have the right amount of bite relative to work-rate… I’m underpropped.
My boat came with a folding 2 blade 15/10 fixed, in place of (what I believe to be standard Catalina factory release) fixed 2 blade 14/11. At first I assumed the lesser pitch on the replacement folder was the issue. Due to potential long term issues associated with underworking the diesel / not wanting to ever be caught on a lee shore in a blow without enough drive to effectively get off / and just wanting to charge around the harbour more efficiently - I’m now looking into getting this sorted.
I definitely want to stick with a folder, but don’t have budget for an outright replacement folder/feathered. So I’m looking to replace blades on the existing Volvo stock during annual haul out this coming southern Spring.
In discussion with a diesel mechanic prop supplier, he explained a 15/10 should give at least a like performance to a 14/11 on basis the extra open blade diameter should make up for its lesser pitch (that opinion subsequently backed up by a 2nd prop supplier) so he was a bit surprised. I then sent him the attached data sheet for the boat, his thoughts are the boat might come out of the factory a bit underpropped on basis a 2YM15 shouldn’t quite rev to 3670rpms with the right amount of prop resistance. He suggested going for a bit of increased pitch - above 14/11 - to ensure I get a noticeable improvement and to justify the exercise.
To keep this economical I want to get replacement blades that achieve a result however at the same time without over-propping (and potentially setting myself up for long term issues in that direction). So I want to try and get this right first pass, done during ant-fouling and back in the water same day - without any follow up haul out remedial buggeration.
To that end... I’m curious to know from any other C275 owners (those with inboard auxiliary & saildrive):
What is your prop diameter/pitch? Are you getting 6.9-7.0 knots with it?
Cheers
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