watertight bulkhead

[Pammie]

You all convinced me to look further than Gerr's method a while ago. So no problem to comply with Rules. However: Complying to Rules might be important for official instances as insurance companies, as a sailor it is important to be able to trust the boat in situations it is heavily loaded. Especially when you're tired and cold, it is dark and the rain is pouring down. So for me Rules are a method to convince me of that. And after that the boat itself has to convince me of it.
Maybe the "small" passengerboats you are talking about have less weight constraints? Do any of these boat have weak spots? What do you think is the chance they encounter a situation they can't handle? What is the dependancy of human errors? Could it be that you are talking about legal safety and I about emotional safety?

 

[rxcomposite]

Maybe the "small" passengerboats you are talking about have less weight constraints? Do any of these boat have weak spots? What do you think is the chance they encounter a situation they can't handle? What is the dependancy of human errors? Could it be that you are talking about legal safety and I about emotional safety?

Doesn't matter. You can make it heavy (displacement) or you can make it light (light displacement) plus the speed to length (Taylor's number) of the boat plus the sea state the boat will be operated on. 3 conditions.

In ISO you can choose if you are going to operate the boat in sheltered waters, inshore, offshore, or ocean. This type of operation is coupled with the corresponding sea state, that is the force of the wind and the height of the wave. This is the same as with other Classed rule except for the definition of terms and the sea state or range to refuge (range to shore).

The type of operation will also show what vertical acceleration the boat will be subjected to so the boat is designed to withstand the G forces it will encounter. Some rules like LR lets you plot the operating envelope so that the required strength is designed. That is, you can sail maybe 16-19 knots in smooth water but can sail only 5-6 knots in 3 meter wave. Generally, a heavy boat will experience less vertical acceleration while a light boat will be tossed around like a cork.

 

[Alik]

Lets look at costs, say for 300K USD boat, say 12m in length.
Under ISO Recreational craft - we are talking about 10-12K USD for type approval certificate, this includes review of design and visits of surveyor. You use normal small craft grade equipment, with CE-certificates.

With class - we are talking about 40+ K for approval of design, supervision and certification. There might be some extras, say lab costs for testing laminates. Other extras, one needs to buy equipment approved by classification society, this is usually 30% of extra cost, but can be more. Sometimes one might need to get case-by-case approval of equipment, say there were no small DC bilge pumps certified by classification society, so - custom certification of pumps adds to project costs. One might be forced to build heavier boat, just because, say, very conservative min skin thickness requirement in DNV; this means less fuel efficient boat and bigger engines. Cost of design/engineering is also increasing with class. It is a snowball of expenses often with unknown financial result at the end. And to maintain the class, one needs to pay every year... For a small boat, I would better spend this money for maintenance and equipment, to improve real safety, not 'paper safety' Paper won't add much confidence at sea (emotional safety!), but better radar and spare anchor will

 

[Ad Hoc]

Under ISO Recreational craft - we are talking about 10-12K USD for type approval certificate, .....With class - we are talking about 40+ K for approval of design, supervision and certification.

So..why are you moaning about costs if you know using ISO is cheaper?
Why would anyone want to use Class for a simple recreational boat if they know it as more expensive?

Is Class more expensive - yes.
Does everyone know this - yes.
Why are you complaining about the obvious - no idea?

 

[Alik]

Is Class more expensive - yes.
Does everyone know this - yes.

Does the class give more safety for small boat - no.

 

[Ad Hoc]

Repeating again, why complain that Class adds cost, don't use them then! Simple...

Does the class give more safety for small boat - no.

Where is the evidence of this? It is still just an opinion.

So, just to be clear, you happy that you're able to use ISO rules for this boat:

... we got recreational boats licensed to carry 20+ persons which are not passenger boats.....

 

[Alik]

Where is the evidence of this? It is still just an opinion.

Says who? Quote?
My opinion has at least same value as Yours. Both by education and experience.

 

[Ad Hoc]

..My opinion has at least same value as Yours.

In case you haven't noticed, i'm attempting separate opinion from fact. You're only supplying opinions - which it seems the armchair designers devour

So, again, just to be clear, you happy that you're able to use ISO rules for this boat:

... we got recreational boats licensed to carry 20+ persons which are not passenger boats.....

 

[Alik]

In case you haven't noticed, i'm attempting separate opinion from fact. You're only supplying opinions - which it seems the armchair designers devour

You showing no facts. There is no official document, saying that small craft with class is safer than boats without class. Instead, most of administrations do not require any class for small craft.
So this is just Your opinion vs mine

So, again, just to be clear, you happy that you're able to use ISO rules for this boat:

Yes, I am quite happy, we do it for many projects. If You look at any recreational boat built to ISO, say Lagoon or Sunreef catamarans, they are all certified for over 12 persons, often over 20 persons. Most of these boats are used for charter.

 

[Ad Hoc]

Good to see you playing/working with the rules to get around issues, we all do that...

Yes, I am quite happy, we do it for many projects....

So, you do not see this, using ISO creatrational category, for a 20 pax boat as dumbing down and a lesser safety than if it were categorised as a commercial boat?

 

[Alik]

Good to see you playing/working with the rules to get around issues, we all do that...

Post a quote from official document showing that boat with class is safer than boat with no class.

So, you do not see this, using ISO creatrational category, for a 20 pax boat as dumbing down and a lesser safety than if it were categorised as a commercial boat?

Did I say it is a passenger boat? Quote?
FYI, boats certified to ISO are allowed as commercial boats in many jurisdictions. Also, Australian NSCV officially recognized ISO for structural design, for coastal categories/length limitation.

 

[Ad Hoc]

Post a quote from official document showing that boat with class is safer than boat with no class.

It is you that is stating Class provides a less safe boat, thus the onus is on you to provide evidence as you made the statement.

Did I say it is a passenger boat? Quote?

Didn't say it is a "passenger" boat.

I'll ask again, with emphasis for clarity
So, you do not see this, using ISO creatrational category, for a 20 pax boat as dumbing down and a lesser safety than if it were categorised as a commercial boat?

 

[Alik]

It is you that is stating Class provides a less safe boat, thus the onus is on you to provide evidence as you made the statement.

OK, so there is no document. Thus, it was just Your opinion that classed boat is safer. My opinion that it is not, and can be less safe.

So, you do not see this, using ISO creatrational category, for a 20 pax boat as dumbing down and a lesser safety than if it were categorised as a commercial boat?

On recreational boat there are no passengers, by definition of ISO

 

[Ad Hoc]

On recreational boat there are no passengers, by definition of ISO

For someone who thinks rules are:

You have nothing to offer other than quotes from the rules. No value...

You are quoting them a lot now

So, if you wish to as per ISO definitions for clarity:
So, you do not see this, using ISO creatrational category, for carrying 20 'crew' in a boat, as dumbing down and a lesser safety than if it were categorised as a commercial boat?

 

[Alik]

So, you do not see this, using ISO creatrational category, for carrying 20 'crew' in a boat, as dumbing down and a lesser safety than if it were categorised as a commercial boat?

Again, we are not licensing any boat for commercial service. Maritime authority does. I don't see where is 'less safety' if the boat designed to ISO, compared to classification society rules or commercial craft codes. Some small commercial craft rules/codes refer ISO standards, say, MCA, NSCV, DNVGL St.0342 do that.

We did a lot of research of small commercial craft, and projects for which we did calcs both to commercial craft standards and to ISO. Say, for stability, ISO is more tough (compared to IMO intact stability code) as takes into consideration typical small craft scenarios, such as overloading, combination of crowding at bow/stern with offset load, etc. Moreover, few times we sent proposals to maritime administrations, in respect of their use of ISO standards for small commercial craft, suggesting some easy but important additions/limitations. We also published number of papers, say we discuss stability margins for overloading, layout principles/passenger protection, styling, acceleration comfort, etc. for different types of small passenger craft. So we live in real world and keen to design safe efficient small craft but also affordable for the customer; we take design/naval architecture work as creative but responsible process.

And now sorry, I have to leave this thread as it goes into pointless discussion with 'quote-the rule' guy I am not quoting but creating Now working on paper about stability, to cover accidents happened in Phuket coupe of weeks ago. Bringing awareness is important part of marine designer's job.