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#1 2021-11-24 14:08:48
- Mo_Jefferies
- Additional Member
- Registered: 2011-03-14
- Posts: 29
Help with prop sizing please!
We're in the process of replacing the Volvo 2010 on our V800 with a Beta 14. The original prop was a Vetus 2-bladed 12x10RH. We've been advised by the 'prop people' that a 12x8.5 2-blade or a12x8 3-blade would work with the Beta.
We noticed that a previous poster had opted for a 13" 2-blade but hadn't specified the pitch.
Our stern tube doesn't leave enough clearance for a feathering prop.
Can anyone help us to choose a suitable fixed prop please?
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#2 2021-11-24 18:15:57
- Kevin_Misselbrook
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- Registered: 2017-05-26
- Posts: 42
Re: Help with prop sizing please!
Hi Mo,
It may be worth your while completing the form on the Betamarine site at https://betamarine.co.uk/seagoing-propellers/
They will then assess all the data you provide about your boat (which includes whether you want a 2 or 3 blade) and they will then make a recommendation.
I have a 13 x 9 three bladed prop in my Frances 26 with a Beta 16 but looking at the general guidelines on the Betamarine site they reckon a 12 x 9 for a boat with the Beta 14.
But ... if you complete the on-line form then they will be able to give you a more educated assessment based on the characteristics of your V800.
Last edited by Kevin_Misselbrook (2021-11-24 18:18:04)
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#3 2021-11-25 10:53:18
- Mo_Jefferies
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- Registered: 2011-03-14
- Posts: 29
Re: Help with prop sizing please!
Thanks Kevin,
We've already done what you suggested, and just wanted to check what other owners with the same engine found was best for them. We are trying to avoid multiple attempts at finding the right prop, a process that others may have been through.
We are also interested to find out any differences people may have noticed in sailing performance moving from 2 to 3 bladed.
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#4 2021-11-25 15:31:28
- Murray_Fraser
- Member
- From: Weymouth
- Registered: 2016-11-22
- Posts: 87
Re: Help with prop sizing please!
Hello Mo. I bought my V800 in May this year and it is fitted with a Beta 14 and a Darglow featherstream 3 bladed prop. I do not have the Prop size to hand but will try and dig it out for you but I agree with Kevin about source of advice. Interestingly the previous engine was a Volvo 2010B and the Darglow was retro fitted to this prior to the Beta. There is ample room for the Darglow on my boat including the placement of the anode on the end so a chat to the company might help, I found them helpful. I do not have the Prop size to hand but will try and dig it out for you but I agree with Kevin about source of advice.
I cannot comment on performance as this is my first V800 but I have not found power to be a problem. Depending on sea conditions (and hull fouling) I achieve 5 to 5.5 knots at 1800 revs, well under the engines maximum torque output at 2600 revs. According to everything I have read compared to a 2 blade prop the three blade prop improves 'bite' in the water both ahead and astern.
VICTORIA 800 Dulcibella
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#5 2021-11-25 17:04:05
- Mo_Jefferies
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- Registered: 2011-03-14
- Posts: 29
Re: Help with prop sizing please!
Hi Murray,
Unfortunately the Darglow won't fit unless we replace the stern tube or hack a bit off the rudder.
I would be interested to know the diameter and pitch though if you get chance to find it.
Thanks for the input though!
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#6 2021-11-25 17:06:53
- Mo_Jefferies
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- Registered: 2011-03-14
- Posts: 29
Re: Help with prop sizing please!
Hi Murray,
Unfortunately the Darglow won't fit unless we replace the stern tube or hack a bit off the rudder.
I would be interested to know the diameter and pitch if you get chance to find it.
Thanks for the input though!
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#7 2021-11-27 16:02:51
- Jonathan_Hopper
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- Registered: 2004-03-23
- Posts: 161
Re: Help with prop sizing please!
Mo -
I have used 3 props with my Beta14 - all 3 bladed so cannot comment on differences with 2 blade.
I don't think there is a best, but certainly different characteristics.
Assuming you have the 2:1 gearbox, the 12 x 9 is recommended by Beta. Since that is what was on the original Yanmar it is what Francesca started with. It was good, but in a short chop I wanted to try something with a bit more grip/area, so tried a 13 x 8. This does not achieve quite so many rpm, but is ok. It is certainly better in poor weather, but a a cost of not so good sailing, especially in light winds. Lastly I have a 13 1/2" Featherstream. I think this diameter is too high - 13 would have been better. It is substantially better in reverse so handy at close quarters, and better sailing, but not so good in forward at 'cruising' speed, and certainly do not the speeds that Murray quotes - I too would be interested in knowing exactly what that set-up is. All of these will give more grip than the 2 blade, but assuming the 2 blade can be parked behind the deadwood then your sailing performance will be good, and probably on a flat sea will be compare well to a similar 3 blade.
Which do I prefer? It depends....!
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#8 2021-11-28 14:56:54
- Mo_Jefferies
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- Registered: 2011-03-14
- Posts: 29
Re: Help with prop sizing please!
Thanks Jonathan for sharing your experience.
The new engine does indeed have a 2:1 gearbox ratio.
The 12x10 2-bladed has served us well for 25 years. The lack of bite in a sea has been inconvenient and uncomfortable at times, but I guess you just have to cope with that. I think because we always prefer to sail if we can, and we are on a swinging mooring, the close quarters manoeuvring hasn't been so much of an issue.
We're very interested to find out what props other owners have used that work well for them, and I would be keen to find out what pitch of 13" 2-blade Dingeman fitted on his boat.
We hadn't realise before embarking on this project, just what a black art prop speccing seems to be! I think you may have mentioned on a previous thread that the logical way is to start with the prop and then work out the appropriate engine and gearbox to suit!
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#9 2021-12-01 17:36:59
- Murray_Fraser
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- From: Weymouth
- Registered: 2016-11-22
- Posts: 87
Re: Help with prop sizing please!
Mo, Jonathan, I was down at the boat today and noted down my prop details. It has raised an interesting question for me as I have discovered that the Darglow Featherstream was fitted to the previous engine, a Volvo MD2010. This has a gearbox ratio of 2.4:1 whereas the Beta 14 is 2:1. The prop is a 13x8 and the pitch cassette is Forward 19:1 and Reverse 17:1. Frankly I am not absolutely clear how the cassette alters the prop performance and need to better understand this as you can purchase different cassettes from Darglow. I am going to contact Darglow and ask them if the prop/cassette that was fitted for the Volvo is optimium for the Beta but I think I need to do some speed measurements first as described on theri website. Hope this helps and doesn't confuse!
VICTORIA 800 Dulcibella
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#10 2021-12-02 19:15:25
- Jonathan_Hopper
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- Registered: 2004-03-23
- Posts: 161
Re: Help with prop sizing please!
Murray - thanks for the interesting post.
From memory, Featherstream suggested starting with a 13 x 8 or a 13 1/2 x 7 1/2 to see how this loaded the engine, and look at max rpm. We went for the latter on the assumption that it was easier to lop a bit more off than stick it back on. Max rpm at the time seemed the main driver for the decision. For the 13 x 8 fixed I got 3,200 max, as I do with the Featherstream. The cassette will presumably alter the pitch, so it will be interesting to hear if a change is beneficial - what max rpm do you get with what you have (clean!)? It may well be that the Volvo would have been able to rev to the max, but the Beta more restricted
For the record, with a clean hull and prop, and with a boat load of cruising clobber, I get 5.2kn at 2400 rpm, increasing by 0.1kn every 100 rpm up to a max of 5.9kn at 3200 - flat sea no wind. If yours is substantially better than this then I might have to get it re-cut! Francesca's blades are made from the larger profile blade in an attempt to keep the blade area up - the slightly smaller blade may well rev higher for the same diameter+pitch.
Apologies to Mo for branching out in this way!
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#11 2021-12-03 19:06:42
- Murray_Fraser
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- From: Weymouth
- Registered: 2016-11-22
- Posts: 87
Re: Help with prop sizing please!
I'll let you know what Darglow say. They need the job number etc. so I hope to get that this weekend. Biggest issue is first to make sure my log is reading correctly and secondly to find a flat sea day to do the RPM versus Log speed plot! Boat coming out at Xmas so not a lot of days left to do this.
VICTORIA 800 Dulcibella
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#12 2021-12-03 23:18:45
- Mo_Jefferies
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- Registered: 2011-03-14
- Posts: 29
Re: Help with prop sizing please!
Jonathan and Murray,
This information is really useful. Hearing about what works for other people is fascinating and hopefully will help us in our search for the 'ideal' prop.
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#13 2021-12-05 00:35:14
- Bill_Robinson
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- From: Langkawi, Malaysia
- Registered: 2021-06-14
- Posts: 110
Re: Help with prop sizing please!
I have just fitted a 3 bladed 330 mm MaxProp Easy to my Victoria Frances 26. I considered the Darglow, and others, but selected the MaxProp based on owner’s recommendations, and my previous experiences with MaxProp. I also replaced the Yanmar with a Beta Marine 16. I also replaced a chunk of the original rudder cut out, but made sure that I could remove the prop, without having to first remove the rudder. Performance under power is hugely improved of course, and I expect under sail as well. No chance to sail her yet as I am waiting for my new sails to arrive.
I have lots of photos which I could send via email.
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#14 2021-12-05 21:00:41
- Murray_Fraser
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- From: Weymouth
- Registered: 2016-11-22
- Posts: 87
Re: Help with prop sizing please!
All, I have heard back from Darglow; superb customer service I would add. For the Beta 14 @ 2:1 they recommend either a 12x9 or 13x8 3B propeller to allow near to full RPM at throttle wide open. They have suggested that after 11 years it may be worthwhile having the pitch checked on mine and if needed a replacement cassette fitted; I understand the cassette can wear over time causing the pitch to alter. I am going to do my sea trials first, if weather allows.
VICTORIA 800 Dulcibella
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#15 2021-12-12 14:14:42
- Mo_Jefferies
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- Registered: 2011-03-14
- Posts: 29
Re: Help with prop sizing please!
That's really useful information B8ll and Murray.
I've contacted several prop suppliers, and they all seem to have a slightly different opinion.
Great to have a real world viewpoint!
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#16 2021-12-13 21:21:51
- Murray_Fraser
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- From: Weymouth
- Registered: 2016-11-22
- Posts: 87
Re: Help with prop sizing please!
Well a bit more real world stuff. Calm day in Weymouth Bay so out I went. Discovered two things. First despite removing the log half a dozen times I could not get it to work in the water! Hand spun it showed a reading on the screen but back in the water no deal. SOG was around 4.4 Kn so not encouraging and I do not understand the difference from my previous 5/5.5 Kn. Second, I could only get 2400 rpm out of the engine; much to my surprise. This is 200 rpm below maximum torque. Darglow's comments about the cartridge wear may be the culprit but I need to fix the xxxx log first. May not happen this side of April now.
VICTORIA 800 Dulcibella
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#17 2021-12-16 15:10:26
- Mo_Jefferies
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- Registered: 2011-03-14
- Posts: 29
Re: Help with prop sizing please!
Hope you get these issues sorted soon Murray. It would be interesting to find out the cause of your lack of rpm, couldn't be weed or concretions?
We had a similar problem with our log impeller. It turned out that we had sneaky concretions hiding way up in the impeller housing.
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#18 2021-12-17 16:47:49
- Jonathan_Hopper
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- Registered: 2004-03-23
- Posts: 161
Re: Help with prop sizing please!
4 or 5 years ago at the end of the season I had that many barnacles on the prop than it would only rev just over 2,000rpm, with a max boat speed, flat calm, under power of around 2 kn. Hard to get out of the marina like that!
I recognise the log issue as well - I can only think that there is occasionally growth on the outside that lodges in the wheel as it starts to spin, or so much growth around it so the water stream across it stops. My log is now combined echo on the wooden block facing downwards, and it hasn't been so much of a problem now that it isn't flush with the hull.
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#19 2021-12-17 23:49:47
- Murray_Fraser
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- From: Weymouth
- Registered: 2016-11-22
- Posts: 87
Re: Help with prop sizing please!
Had a look, at the prop today as water flat calm.....weed for sure and perhaps a few barnacles so you could both be right. Jonathan I have a raymarine 800 tri - log, depth, temp. I did wonder about trying to extend it further below the hull. How did you achieve this? Also of gluing(?) a piece of copper to the side of the the protrusion especially as my hull is already copper coated.
VICTORIA 800 Dulcibella
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#20 2022-04-19 21:57:50
- Jonathan_Hopper
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- Registered: 2004-03-23
- Posts: 161
Re: Help with prop sizing please!
Murray - I have been meaning all winter to post a couple of photos of the fairing block on Francesca. It was originally factory fitted (as a Stowe sounder), and I just enlarged the hole for the DST800.
Inside the locker is now partly partitioned so that any ingress of water whilst cleaning the impeller can be contained.
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#21 2022-04-22 21:14:56
- Murray_Fraser
- Member
- From: Weymouth
- Registered: 2016-11-22
- Posts: 87
Re: Help with prop sizing please!
Thanks Jonathan this looks identical to mine, inside and out. Clearly a fouling issue. Interestingly, there are two sealed openings in the locker between the forward berths. I assume these were for seperate depth and log instruments. Seems a much better place frankly but I am not going to drill them out now.
VICTORIA 800 Dulcibella
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