Hi all sorry if this is in the wrong thread

DanFox

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Hello everyone I'm trying to find out the size of the propeller on a AF/Broom ocean 30 but can not find any info on the size or pitch, I'm looking at getting one one day either the AF or Broom, I just want to get an idea on the size and the clearance from the tip to the hull and the rudder arm, Oh and is the hull a displacement or a semi displacement, and what is the cruising speed and max speed, I've seen so many that say top speed is 11knots to 9 knots and even 8knots, as well as saying the hull is a displacement and others saying its a semi displacement

Tar Dan
 

Dino

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Not sure about prop size but I’d says it’s definitely a displacement hull. The ones I know of mainly had single engines and the twin engine versions only had two forty something horsepower Mercedes or Perkins. I’d say 9-11 knots would be optimistic. More like 6-8 knots. Most single engines ones are ex hire. Some had a single aft cabin or a double and some had no aft cabin.
 

oldgit

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Thanks for the info and it looks like a stable boat on the sea as well and looks like the trough is about 1/2 the length of the hull with good wave dispersion as well
....from your other post get the idea that the boat will be used on non tidal waters, would suggest either of the boats would do the job nicely but suspect the Broom 30 with its larger internal area would be better regards year round boating and the English weather.

Owned a 37 ft hull moulded by Aquafibre and fitted out by a company called Transocean, can confirm it was laid up like the proverbial brick outhouse, the seakeeping qualities of the hull was somewhat less impressive compared to hulls of more modern design.
 
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DanFox

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....from your other post get the idea that the boat will be used on non tidal waters, would suggest either of the boats would do the job nicely but suspect the Broom 30 with its larger internal area would be better regards year round boating and the English weather.

Owned a 37 ft hull moulded by Aquafibre and fitted out by a company called Transocean, can confirm it was laid up like the proverbial brick outhouse, the seakeeping qualities of the hull was somewhat less impressive compared to hulls of more modern design.
https://www.jonesboatyard.co.uk/boat-sales/documents/Ocean-30.pdf In the manual from AF It's a sea going boat but
And from a Surveyor says the same thing Ocean 30|Pre purchase survey|European Marine Services | European Marine Services Ltd, That one has been fitted with bilge keels which will help with rolling, And with the box keel added ballast will also help, A lower the G to M Will give a stiff boat so faster rolling but a greater GZ so can heel further,
 

DanFox

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You'll need engine power and revs plus gearbox ratio to know what the propeller size will be.
From what I've found out is 2 om636 engine's at the 42hp max rpm of the 3500 with a 2.09:1 the prop need is a 15.5"X13" for 7 knots which need's 12Hp at the prop, with the existing hp at the engine the top speed it 13 knots, That's the reason why i was trying to find the size of the prop as the original seams under propped, the total hp at the prop is 80.2hp and 229 ft/lbs,


Found it out on here ( Vicprop - Prop calculator for Displacement and semi-displacement hulls ) and put all of my dad's 1989 lochin 38 details in as well and it gave the props which were the size that he got told to put on in testing, which were 21"X19"
 

oldgit

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Sometimes in non tidal waters being under propped is a tad is useful ,charging batteries on very short trips and more prop wash over rudder giving greater rudder authority at manoeuving speeds ?
Must say having used internet prop calculators merely to confirm my boat had the correct props, do not recall any of them actually agreeing with the props already fitted on the boat.
A tale of two Turbo 36s, virtually identical, one had 3 blade props and one had four blade props, annoyingly for one skipper the other boat was always faster.
This rankled mightly and he was of course advised to fork out a small fortune for a set of props with whatever number of blades the other and faster boat was fitted with.
Some helpful prop seller sold him a shiney pair of what ever size and pitch he needed to get the same blade area etc.
It made not the slightest difference.
The old props were refitted and when the boat was sold shortly afterwards the new owner got a brand new set of props included in the sale.
 
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