Jaysen's Mini 580 plan -- on indefinite pause :(

[Jeff]

OK, now I am clear as I was sure you had received the approval to use 9MM. We can discuss the options of Okoume BS1088 versus Meranti BS1088. I will also check the weight of each so you have that information!! Jeff

[Jaysen]

Thanks Jeff!

One of the "gotchas" here is that there is a minimum hull weight for the structural hull after glass. While I need to keep it light I need to make sure I don't undercut it too much. There are a couple of other discussions I want to have with designer/association about the use of timber frames vs ply frames that may change the glass and wight conversations. All in all the basic build is pretty straight forward. I just want to make sure the limited supply of "matching" products doesn't get me into trouble.

Examples:
* 200g/600g do not actually match up with 6oz/17oz (light) so we need to get approval for that.
* The reliance on timbers not readily available in the US (larch is a large portion of the frames hence my desire to make them from ply )
* The resin called out seems to have an odd ratio/weight (weight based ratio that is variable based on hardener).

I'm confident that we can get the hull made with all BBC materials. I just want to have the conversations with the designer/association before we start laying out the cash.

Unlike Lil Bit, the hull and epoxy really will be the cheaper part. My current guesstimate for the unfitted but completed hull is right around $5k. I'm probably a bit under. I'm guessing I'll over buy some things (ply, glass) and under buy others (how many gallons marin == 22kg? and can I be that exact on consumption... and oh, btw, I need to do a full layer not just seams so... bah!)

Anyway... I'm enjoying the planning so far.

[terrulian]

Does the $5000 count all gear? That seems unlikely.

[Jaysen]

Does the $5000 count all gear? That seems unlikely.

Heck no! That's just the hull completed to paint. No outfitting. The target cost for these completely outfit is €20k so figure $us25k. I'll look on the used market for something things that can be reliably sourced (winches, cleats, blocks) but will go new for the the critical (mast, boom, sails, etc). I'm also committed to making some things like the windvane.

[fallguy1000]

News from the Mini 580 team: 9mm is adequate for the hull but will require extra layer of glass. There are questions about needing to lam to 9mm to 18 vs buy sheet of 18mm for keel panel (I'm a troublemaker). This is good news as it lowers the cost enough to move from Meranti to Oakume or, considering that this hull will most likely get injured regularly, start a repair fund Will need to chat with Jeff on which ply I want. Oakume seems like the smartest as I'll need to counter the weight of extra glass.

Poor Jeff... more PM from me are coming his way!

Make sure you understand the cube rule before deciding a thickness change. You can't achieve it with glass without creating an excess of weight.

Basically thickness creates stiffness.

1mm^3 = 1
2mm^3 = 8
9mm^3 = 729
10mm^3 = 1000

So, while 2mm is twice as thick it is 8 times stiffer and 10mm is 10 times thicker, but 1000 times stiffer.

[Jaysen]

In this case we are going from 10-9 and 20-18. The stiffness should be able to be made up with glass but there will be a weight penalty. I'm thinking that I can mitigate some of that with oakume.

The designer has been involved with the changes (this is a class wide change). He agrees that the 9mm would be completely satisfactory for the hull. They are adding glass layer to make up for "worst case". The actual plans have glass only in the seams. Personally I like the full coverage.

[terrulian]

With regard to cost: Your plan is a good one. It is also possible to buy a refurbished life raft, or buy a used one and have it serviced, as it will be one of the big expenses. I'm not sure that would satisfy the rules. I didn't have the nerve for that and bought a new one.

[Jaysen]

With regard to cost: Your plan is a good one. It is also possible to buy a refurbished life raft, or buy a used one and have it serviced, as it will be one of the big expenses. I'm not sure that would satisfy the rules. I didn't have the nerve for that and bought a new one.

My recollection is that all safety devices (pirbs, rafts, etc) had to be new. I'm budgeting about $5k just for that. Only need a four man raft so it isn't too bad. I may get used for early runs (non-racing) as that will delay that expense a bit.

[fallguy1000]

In this case we are going from 10-9 and 20-18. The stiffness should be able to be made up with glass but there will be a weight penalty. I'm thinking that I can mitigate some of that with oakume.

The designer has been involved with the changes (this is a class wide change). He agrees that the 9mm would be completely satisfactory for the hull. They are adding glass layer to make up for "worst case". The actual plans have glass only in the seams. Personally I like the full coverage.

You do realize a millimeter of ply is lighter than a millimeter of glass n resin?

So, if you are adding another layer of 6 oz glass; not sure if that is a millimeter, but for racing..

Is this just a sourcing issue?

[Jaysen]

Yes. Glass heavier. 2-4mm wood is heavier too. The option was 10 or 12 and we successfully argued that 12 would not bend to the curves. That left 9 with concerns of strengthening which resulted “more glass” solution. I think we are good though as now the entire hull is one size ply. I may clean out Jeff’s 9mm at some point.

And yes on sourcing. The architect is Poland. Poland still has 10mm ply. It isn’t just US but many other build areas that only have imperial equivalents available.