Mapping Center Answer:

This is one of those hand drawn symbols that has never translated well into digital mapping, at least not without an explicit effort to draw a particular symbol like this. 

Part of the issue is that the symbol is actually an outline for a polygon, so it must ideally curve around a coral bed, giving an indication of the structure.

We did a blog entry not too long ago that used cartographic representations to do a scallop type of line--that worked well enough because the circle marker symbol could be used. In this case you could create some roughly "U" shaped marker symbols.  I tried and couldn't get anything that looked excellent--the ends of the Us crossed and the look of the symbol wasn't intuitive. Basically due to the curving (or lack of) issue you described.

So, I went back to basics and created a line feature class and literally drew the symbol as series of line features. 

I symbolized the features as unique values so you can see the extent of each feature. I drew only the first six or so features using vertex snapping to make sure they connected. Once I had a decent looking sequence I copied and pasted them to speed my way through creating a boundary for a single reef/bed.  Once I pasted each group, I used the Rotate tool near the end of the Editor toolbar.  I used the modify features task to adjust the interior pointing prongs when they needed to look better.

In all, it took about about 3 minutes to create the features that constituted this image.  It's slower, but definitely looks better.

To save even more time, once you have few beds of different sizes and typical shapes created, you can just copy and paste them, and then convert the features to cartographic representations and use the Direct Select tool and the Warp tool on the Representations toolbar to adjust the shapes to fit the real-world boundaries of the beds/reefs.  Below is a quick example of that sort of editing, and it took about 30 seconds to produce: