The short answer (Yes the number of life jackets)

A better answer, a number that does not inhibit the boats operation.  You can see this on your boat. Have all that are going stand on one side of the boat on (one rail) at the dock, adding one by one until you hit about 12Deg of heel. (That is it)  or an est for the w28-  four (Normal big crew) + a couple guests  so your base # may be in excess?   If everyone is under 170# the you may be ok+/-  ? don't know.

Please check out the below report where the captain killed 2 people (an ugly Ugly thing! it is to bad we can't shoot stupid). 

http://www.signonsandiego.com/news/2011/mar/27/two-dead-boating-accident/

Just remember not all the other boaters observe the no wake zone, and if all of your passengers get, or move, to one side or back to the cockpit you can get into big trouble fast. I think I would pass on the extra passengers, at least if you are going out on the water.   At the dock Tied up = No wake, No wind, no swell, nearby dock;  and haveing them spread out down below, in the cockpit and on the fore deck  I have had 13 onboard; no way a seaworthy condition in my mind,  I have a w32 and I would not go out with more than 7. I also make sure all know (NOT TO ALL GO TO ONE SIDE  OR ONE END and I require everyone to where a lifejacket! some places it is the law!) 

Please think about what you are doing always!, and indeed the water is one of the nicest places to see fireworks!         HAVE FUN and SAFE!!  4th.

 

Norm