Is Foam Core Better?

As a general rule foam cored construction (in good condition) is stiffer and lighter than the equivalent all glass layup. I can't comment on your specific situation since I am not that familiar with the 5.8 but the sales pitch sounds eminently plausible.

Is the '84' boat also foam cored? With boats of this age condition accounts for a lot. If a foam sandwich boat is showing signs of delamination or damage/neglect, a single core boat could be preferable option from a maintenance/repair point of view. View both craft and take a suitably knowledgable friend with you.

Cheshirecatman

Also look for these little tubes on the inside. They look like toilet paper cardboard that have been glassed in as a stiffner. I have seen them cracked away from the hull, dont remember the model...

Yes, by 50 pounds. The newer are also stiffer and have more bulkheads. Price may be better considered by sail condition, trailer, and overall package.

Had coffee with Tom Roland one morning before a race; he designed the NACRA 5.2.

Got to talking about this same question as to what he thought was better. A comment he made still sticks in my head;

you could hit the original 5.2 with a sledgehammer and it will keep sailing.

They were the fiberglass (non foam core) boats.

Good luck!

The 5.8 is a beautiful boat and the basic rule I've found is the newer they are the lighter they are. All up ready to sail the 84 model probably weighs around 200kg, the 87 around 180kg, a new one weighs around 160kg. I'd lean towards the newer one but condition of sails, tramp etc would decide the job. Have they both got the NA bow foil and big jib? Have they both got original masts as the newer masts are a fair bit lighter and easier to raise so if one was replaced in the last few years it would have an advantage
Good luck with your purchase and post pics

Stiffness and strength are linked together in a fiberglass boat. To have a hull of proper strength you must have stiffness. Stiffness keeps the hull from deforming. Stiffness can be achieved by building up a thicker laminate (adding a lot of weight), a relatively thin laminate with an extensive stringer system (also adding a lot of weight), or by spitting a relatively thin laminate and moving the now two laminates apart with a structural core material. You can take a given laminate (for discussion purposes say 1/4

thick, split it into two 1/8

laminates and put a 1/4" core in between it and by doing so increase the stiffness of the panel by a factor of 7 times (700%) and increased the panel strength by a factor of 3.5 (350%) yet only increased the weight of the panel by a factor of .03 (3. %).

A cored hull is much stiffer than a solid glass hull of equal or slightly thicker skin. There are engineering guide lines that dictate how large a panel can be without being supported by some type of internal stringer support. Cored hulls, have a higher panel stiffness, and therefore can have internal bracing members farther apart compared to what would normally be used in a solid skinned hull.
If a hull has insufficient stiffness there is a possibility of cyclic loading that is similar to bending a paper clip back and forth...over time it is weakened and the panel fails.

For more on how cores work to increase stiffness in a composite laminate copy and paste this link and go to page 18 out of 24 of the PDF file (marked page 79 figure 2-13).
http://www.marinecomposites.com/PDF_Files/G_Composite_Materials.pdf

The fact that you would be hard pressed to find a single skinned performance catamaran from any builder ought to speak volumes as to what direction you should go all other things being equal. A single skin may not dent as easily as a cored hull, but that doesn’t mean that it is better when all factors are considered.