Oyster Problems?

[neilpride]

Originally Posted by jmaja

Swan 66 is not CF boat, but has some CF structures.

Swan 60 is made in Carbon, I don't mention the 66, but you right it have lots of carbon to in the structure.

[Polux]

Originally Posted by neilpride

Swans this actual days are made in CF , hull and deck In the 60 ft and the 80 ft, so no sense in compare a Poly Oyster hull with a CF Swan in terms of strength,, Swans are the kind of Light, Strong , Fast and rally expensive boats....

One of the last Swan models is made without a cored hull and in GRP, I mean, like Bavaria's hull and the other that was refereed by jmaja, also a recent model, has the same type of hull as Oysters, solid laminate under the waterline, cored hull above with carbon reinforcements and the same type of resins are used. On that post only the big 80ft is a carbon boat and much lighter than the comparably 80ft from Oyster.

This is the Oyster 66 that jnaja was talking about, with similar built to Oysters, except that it has carbon bulkheads. That should make it comparatively lighter compared to Oysters, but the hull is probably not lighter and the boat, taking in account all I said and the difference in length for the 625 is on the same weight frame.

[jmaja]

Just to understand how DLR changes with size I made earlier a comparison of current Swans, but the bigger ones are carbon, so it's not a fair comparison.

So lets look at S&S Swans from late 70's. They are likely built to be about equally (and enough!) strong and from same materials. All values from S&S Swan Association

Swan 38: 8.5 tonnes, LWL 8.75 m, DLR 353
Swan 411: 10.8 tonnes, LWL 10.23 m, DLR 281
Swan 47: 14.7 tonnes, LWL 11.05 m, DLR 303
Swan 57: 22.5 tonnes, LWL 13.96 m, DLR 230
Swan 76: 44.8 tonnes, LWL 18.7 m, DLR 190

So it clearly shows a lowering trend in DLR with increasing size. That is because beam and draft do not increase linearly with size and also because material thickness does not increase linearly with size. Not that the bigger Swans would be very much more racier. Clearly the typical classification by DLR does not work for different sizes. Swan 38 would be a "Heavy cruising auxiliary boat" and Swan 76 "Light ocean racing boat" according to Ted Brewer (e.g. http://www.sponbergyachtdesign.com/t...n%20ratios.pdf). Both equally untrue!


Oyster 55 with 23/26 tonnes, 13.85 m, DLR 241/272 fits well in that series of S&S Swans.

Also Oyster 825 with 56 tonnes, 21.97 m, DLR 147 (or 164 in the IRC certificate of Maegan) fits well in the S&S Swan trend, since it has much bigger LWL than Swan 76. But that is extrapolation, since that big S&S Swan doesn't exist.

So the old Oyster 53/55 seems to be built with heavy scantlings and 825 with much lower thickness even though the size would ask for more.

I still can't understand where did they put all that weight in 825, if the hull is clearly thinner than in 53/55.

[jmaja]

Originally Posted by Polux

One of the last Swan models is made without a cored hull and in GRP, I mean, like Bavaria's hull

AFAIK Bavaria uses cored hulls in all their models. Beneteau and Jeanneua uses single skin hulls in many models and Swan used to have all hulls single skin in the past.

[neilpride]

Swan built like a Bavaria, haha, you really funny Sr.

[TeddyDiver]

Remember with 'light CF hulls' it doesn't allways mean the boat should have light displacement too. It just gives weight to ballast and whatever tankage or fancy luxory 'hevily loaded' buyer wants..

[Polux]

Originally Posted by jmaja

AFAIK Bavaria uses cored hulls in all their models. Beneteau and Jeanneua uses single skin hulls in many models and Swan used to have all hulls single skin in the past.

Cored hulls above waterline only, solid single skin below, like most Swans and Oysters
On the past Bavaria hulls were single skin hulls.
In fact that is an overall better solution than single skin hulls.

[Polux]

Originally Posted by neilpride

Swan built like a Bavaria, haha, you really funny Sr.

Yes, Bavarias built like Swans and Oysters with a hull that is cored above waterline solid skin below. I don't know if Swans and Oysters use like Bavaria Kevlar reinforcements at the bow but I guess they use at least carbon reinforcements.

Meaning they have the same type of hull. Regarding being built with the same quality, between Oyster and Bavaria one wonders about that

[neilpride]

Originally Posted by Polux

Yes, Bavarias built like Swans and Oysters with a hull that is cored above waterline solid skin below. I don't know if Swans and Oysters use like Bavaria Kevlar reinforcements at the bow but I guess they use at least carbon reinforcements.

Meaning they have the same type of hull. Regarding being built with the same quality, between Oyster and Bavaria one wonders about that

I don't take this post as serious, so I guess you must be kidding !!!

[jmaja]

Originally Posted by Polux

Cored hulls above waterline only, solid single skin below, like most Swans and Oysters
On the past Bavaria hulls were single skin hulls.
In fact that is an overall better solution than single skin hulls.

I don't know in detail about the Cruiser line, but Bavaria Matches have cored hull way below waterline. Behind the engine all the way to centerline (except around the rudder bearing). Definetely a better system for the same weight.

[jmaja]

Originally Posted by jmaja

I don't know in detail about the Cruiser line, but Bavaria Matches have cored hull way below waterline. Behind the engine all the way to centerline (except around the rudder bearing). Definetely a better system for the same weight.

At least this Bavaria seems to be cored only to waterline, so maybe all current Cruiser Bavarias are.

[Polux]

Originally Posted by jmaja

At least this Bavaria seems to be cored only to waterline, so maybe all current Cruiser Bavarias are.
..

Yes, they built like that for many now. The Match series were more sportive and lighter boats with a different hull built. Now the only one that is not solid laminate skin till the waterline and cored above is the small racer.

Here you have a good description about how the Bavarias are put together:

Hull and Deck Bavaria yachts
Sailing Yacht Management Team - Bavaria Management

[boatpoker]

Originally Posted by jmaja

At least this Bavaria seems to be cored only to waterline, so maybe all current Cruiser Bavarias are.

I have posted a copy of the damage survey of the Bavaria Match 42 that lost it's keel. You might find it interesting.

[neilpride]

So, in the Bava pic we have the clasic Plastic Fantastic crap, the infamous glued grid liner, with , wait , no beams or partitions in the bow area? and from the picture what is that? a white plastic tank glased to the hull? no framing in the aft of the hull sections?

Definitely the same building practiques , materials and strength that in a Swan, like the 60 footer pictures, full carbon, even the deck...

[boatpoker]

Originally Posted by neilpride

So, in the Bava pic we have the clasic Plastic Fantastic crap, the infamous glued grid liner, with , wait , no beams or partitions in the bow area? and from the picture what is that? a white plastic tank glased to the hull? no framing in the aft of the hull sections?

Definitely the same building practiques , materials and strength that in a Swan, like the 60 footer pictures, full carbon, even the deck...

You missed the statement on their website that their laminate is mostly chopped mat with woven Aramid reinforcement forward only. Not something I'd be bragging about.