CS-17 maximum safe loading

[MisterMoon]

Any idea what would be the maximum "safe" loading for a CS-17 would be. My boat weighs approximately 400 lbs, my feeling based on experience is it would be fine at 1200 lbs displacement. What is ppi increase in displacement above the DWL? 

[Joe Anderson]

There is a previous thread on this but I do not know how to insert a hyperlink or it does not work.

 

http://messing-about.com/forums/topic/4314-capacity-issues-for-camping-trip/page-1

 

typed in by hand not sure if that will work if you cut and paste?

[Joe Anderson]

Most of the thread applies to the CS 20 Graham gives the pounds per inch immersion above the design water line as 375.

[Phil Garland]

For the 2 Everglades Challenges we have done with "La Perla", our CS17 #351, I would estimate we had an all up sailing weight close to 1000 lb with boat, crew and gear.  Maybe a little less the last time as it was lighter conditions and we carried less water ballast.  The first time we had about 130-140 lb. water in jugs tied around the base of the CB case and the boat seemed to handle the heavier conditions well.  We were still quite fast downwind and when we rounded up to reef the sails in a squall, the boat hove- to nicely and the extra weight in the bilge probably helped that.

 

I would imagine that 1200 lb all up would be ok for sailing around in protected waters.  

[MisterMoon]

Having the data point for a CS-20 helps. 

My initial wild assed  guess of the waterplane area at DWL is around 54 square feet (LWL 16' x  BWL 5' X 68% to correct for the pointy bits), Based on that, I estimate 1" of immersion above DWL is around 287 lbs per inch immersion. 

Applying the same logic to the CS-20, I get 375 lbs per inch as Graham did in the other thread using (19 x 5.5 x 68%) = 71 square feet. 

[MisterMoon]

Phil, I have no doubt La Perla is muuuuuch lighter than Bandaloop. My guess for the last two ECs is we are probably between 1,000 and 1,100 lbs all up. We only ever carry at most 6 gallons (50 lbs) of water for two people. 

[PAR]

A 400 pound CS-17 is a bit on the heavy side, but she'll have lots of freeboard left to settle down. I agree the PPI for the CS-17 will be in the 290 pound range, but this will change fairly significantly, once she gets immersed a bit. As designed (Graham's data would be helpful), assuming about 300 pounds for a full up CS-17, you're likely in the 650 to 700 pound range with a crew of two, reasonable trim, some modest amount of gear and water. Setup for a raid or the EC another few hundreds pounds could sneak aboard. I'll bet Graham has estimated a bit higher than this, given the nature of the average build and the usual need for a beer cooler or two. I'll guess 900 to 1,000 pounds for two and a few days of supplies.

[Ken_Potts]

   I can't make a good estimate of weight but I've packed enough to keep two people quite comfortable for 6 days.  That's tent, sleeping bags, air mattress with pump, chairs, extra screen-tent in case the bugs got bad, folding table, stove (big old Coleman 2-burner), pots and pans, dishes, food, beer, wine, water, lights, cameras, books. clothes, etc. etc. etc.  During the trip we had to manage some lively weather (not too bad, just small-craft advisories) and the boat felt safe the whole time.  Slower than usual, but safe.  Fun trip, but way too much stuff.

   We did make a mid-trip beer stop but other than that I think we were almost as self-sufficient as homesteaders.

   The maximum safe loading would depend largely on the way things are packed, the weather experienced and (mostly) the decisions of the captain and crew during the journey.  But you already know that

   In the event of a capsize the safe load might also be different depending on whether your boat has a lazarette or is open all the way back to the transom.

[Designer]

When designing the CS17 I recall that my target cruising displacement was 1150#. This does not mean that there is a wall that you hit and the boat is suddenly unsafe. It was simply the median displacement where I optimized her hydrostatics. I have rarely seen good boats that are better by carrying more stuff, with common sense she will carry all that two people will need to cruise for a week or so before replenishing.

 

It has pleased me to no end to see how many good cruises have now been made in her. 

[MisterMoon]

Thanks Graham.

This question is coming from some rather arbitrary 'rules' being floated by Chief in Watertribe. If my boat is on its DWL (an arbitrary line itself) at 1150# and it loading it to 1450# puts it down on its lines one inch deeper, it might be slower but no less 'safe'.

Even as a notorious over packer, I've never felt like the my boat was overloaded. In fact in some respects she feels better with a bit of a load on.

[Phil Garland]

La Perla is not a real lightweight build...she has all the standard design plywood and most hardwood is WRC and CB trunk is Douglas Fir. Taping was overdone a bit for added stiffness.

Hull and deck weighed 300 lb (no blades, masts,booms, rigging or sails). Didn't weigh it all up but would bet it's about 400 lb.

[Tom Lathrop]

I built BRS15 LOON fairly heavy with 3/8 luan ply so she was probably near 300# hull only.  BRS is a lot smaller and less commodious than CS17.  Nevertheless LOON carried two people with all they needed for two and three week cruises along the east coast of Baja in The Sea of Cortez.  That coast is unpopulated with few if any chances for resupply and the wind and water conditions can be boisterous and navigation charts marginally adequate.  I thought the BRS too small for that service but the owners obviously made it in good form.  Read their story on the B&B website http://www.bandbyachtdesigns.com/Baja/Baja%20adventure.htm .  LOON has sailed from North Carolina to Maine to Great Salt Lake to Mexico and is apparently still going. My point is that the CS17 is quite capable of such cruising under good seamanship and supply management.