Latest News: › Forums › Technical › Masthead buoyancy volume, plus outboard bracket query
- This topic has 12 replies, 3 voices, and was last updated 4 years, 8 months ago by
Sylvain Caro.
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- 20/11/2017 at 4:49 pm #25295
Sylvain Caro
ParticipantHello to all,
These are two new questions from France 🙂
1/ Owner of the Wayfarer W3380 Mk1 GRP, I wonder which volume of buoyancy needs to be put at the head of mast to avoid the reversal in case of capsizing.
2/ I saw a lot of Wayfarer owners use a support (named “chair” in french) to support and deport the engine behind the back board of the boat. Is it essential? For which reason is it used? The hull of my boat is made in fibreglass but the back board is wooden. To deport an engine does not risk to weaken the back board by leverage?If this backwardation is necessary, which is the ideal distance?
In advance many thanks to you!
Sylvain20/11/2017 at 5:18 pm #25300Dave Barker
KeymasterHi Sylvain,
John Mellor has written an article on the first subject, which answers your question. I quote the key paragraph here:-
“You could make your own mast head buoyancy, but how much buoyancy do you need? I have seen a 30 litre inflatable buoyancy bag made by Aero Luffspars in use. It was not windy but a 16 stone (100 kg) crew member was able to balance along the mast two-thirds of the way to the spreaders before the mast started to sink, whereas the original buoyant mast gave about 8 litres of buoyancy and I have inverted with this mast.”
20/11/2017 at 5:54 pm #25301Sylvain Caro
ParticipantHi,
Thanks for your answer!
I have readen this, but it speaks about an internal mast buoyancy no?
So I don’t think it has the same effects than if the 8 liters are at the top of the mast…
But Are these 8 liters enought…?HobbiCats use a 8 liters but do they have the same hull weight…?
20/11/2017 at 5:59 pm #25302Dave Barker
KeymasterIt says that 8 litres is not enough (8 litres still allowed the boat to invert). Use 20 or 30 litres at the mast head.
20/11/2017 at 7:09 pm #25309Sylvain Caro
ParticipantOkay, so I’ll make a 20 or 30 litres buoyancy… thanks!
Someone can help me about the engine chair? 🙂
20/11/2017 at 7:40 pm #25310Dave Barker
KeymasterIf you make a forum search for “outboard bracket” you will probably find everything you need (and more!)
The bracket keeps the engine away from the mainsheet, and it keeps the propeller clear of the rudder (most of the time…) It is also helpful if you use a boat tent. But the weight distribution in the boat is not ideal!
The transom (“back board”) is strong enough for a 2.5 hp engine, especially if a backing piece of plywood is added on the inside. The mounting bracket should be “through-bolted”, not just screwed to the transom. Sometimes this is difficult because there may be buoyancy material in the aft locker.
The ideal distance and height are found when the propeller is at the correct depth (with the engine vertical) but the engine body also has enough space, even when the engine is tilted up.
20/11/2017 at 7:53 pm #25311Sylvain Caro
ParticipantMany thanks Dave!
My problem for making researches on the forum, is that I miss a lot of words to make searchs…
As I didn’t know the good translation, I didn’t knew “outboard bracket”, so I founded nothing :-p
So my engine is an old but very nicely cared Susuki 2.2cv.
You’re right, there are buoyancies inside the back box…
But how can I know the correct depth for the propeller?
Does a technic a measuring exists for determinate it?20/11/2017 at 7:57 pm #25312Sylvain Caro
ParticipantAnd you told that the weight distribution in the boat is not ideal with the outboard bracket…
You mean it’s not good while sailing or when you use the engine?
20/11/2017 at 8:10 pm #25313Dave Barker
KeymasterI think the anti-cavitation plate is meant to be approximately level with the lowest part of the keel (at the transom). This will put the propeller in clear water at all times (until you walk forward to the bow, when mooring).
Weight distribution – when sailing. (You would normally carry heavy items near the bottom of the mast).
20/11/2017 at 8:25 pm #25314Sylvain Caro
ParticipantOk!
I use to put the anchors and chain near from the bottom of the mast (I’ve got two anchors, a small one around 2 or 3kg and a bigger one around 4kg, chain around 2 or 3… the engine is around 12kg if I remember… )Thank you for informations about the propeller 🙂
20/11/2017 at 8:27 pm #25315Sylvain Caro
ParticipantMmmm… “transom” means the board who’s at the back of the board?
20/11/2017 at 9:20 pm #25316Dave Barker
KeymasterC’est le tableau arrière en Français, n’est ce pas?
20/11/2017 at 9:39 pm #25317Sylvain Caro
ParticipantOui!! 😀
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