Who know big Passenger Boat ?

we have a customer who want to buy a big passenger boat from us, length 25m, 120seats,single hull, all fiberglass material. But he asked us to make the hull and deck thickness 1.25inches (about 32mm), we asked him how about sandwich structure, he said "no, must be all fiberglass". We think it is crazy, that boat thickness is usually 12mm, with ribs inside, if make 32mm then it would be too heavy. But my customer said "American boat all like that"

Who can give us some idea ?

this is his requirement: One-piece shell fiberglass ( hull and multihull ), with minimum thickness of 1.25 inches

 

Why would you allow a client to dictate laminate schedules? Unless the client can justify his request with some certifiable need, he's just a nut job. Simply put, a 120 passenger craft has to meet many requirements, one of which is appropriate shell scantlings. A sale like this is meaningful, but never let a client dictate scantlings, without also forcing them to jump through the same certification hoops, the original design team had too.

Unlike many businesses, where the "customer is always right", in this business the customer is rarely right, which is why they've come to a professional, so they can get it right. Never forget this aspect, on the business end of things or you may very well become liable for decisions they inappropriately made.

 

Ask for an example of a boat built to the specifications requested. Especially the 1.25" fibreglass deck !

 

I wouldn't bother with a fishing expedition about other designs with 1.25" decks, as it's just asking for the client to control the yacht's engineering, which from a liability point of view, is insane.

 

Reminds me of a sign I saw in a mechanical repair workshop, "hourly rate, $60, if customer helps, $100 an hour." If you ask a man to do a job, you have to trust he knows what he's doing, if you don't, go elsewhere. You aren't the coach, just the customer !

 

Precisely Mr. Efficiency. You go to a professional for only one reason. If this was my client, I'd ask him if he would fly in an airplane, where the wings where designed by the uncertified purchaser.

 

Maybe he wants this for ballistic protection?
Offer him standard laminate and ballistic panels instead!

 

I want to give you rough calculation for the deck weight. lets say your boat will have beam 6 m . let say the waterplane ratio 0.75. the area will be 25 x 6 x 0.75 = 112.5 the volume of deck shell itself = 112.5 x 0.032 = 3.6 m cub.

your laminate is hand layup about 1.6 tons/m cub density

the total weight, is 3.5 x 1.6 = 5.6 tonnes weight as 2 pieces non military humvee.

that is only shell, framing and stiffeners not included.

i saw some passenger boat, but it was sandwich marine ply. but in several stressed area they rebate the marine ply and thicken glass with same thickness, maybe your customer fooled by this

but. if 5.6 tonnes deck shell is wont be a problem for your whole calculation, just go with it. you are not the one who pay for materials right??

 

sometimes i find myself in the same situation. you just have to protect yourself and write it up as built to customer specs and customer assumes all liability.and just charge time and materials based on his design.... . i have done that often...and many times i have turned down the job. you can build 1000 good boats and not be remembered. build one bad one and it will stick forever

 

i have seen two hulls that exceed 2"" thick. but this was D.E.S.C.O. built. full displacement hulls for commercial fishing.. in this case the weight would be to an advantage. these boats are extremely tough boats