How big should a bunker be? Of all the art forms on golf courses, this is the, well….arty-est. Unlike tees and greens which need certain sizes and even shapes to maintain turf, bunkers can generally be any size and shape you desire.
I'm sorry that this ditty will require some editing to be good writing, but here are some play, maintenance and visibility guidelines that I follow, however.
Playability
In terms of play, it’s usually desirable to have enough room for a golfer to swing a club, which is a function of size and depth. Usually, a golfer needs about 6-8 foot width and depth to make a good swing, and any bunker that is deeper than a few feet and smaller than this – which in the great outdoors is a very small bunker, even for a pot bunker – means it may be an unplayable lie.
Maintenance
If I am designing “cape and bay” bunkers with several lobes and the superintendent wants – and most do – to rake the bunker with mechanical sand rakes, the minimum diameter those can negotiate on gentle slopes is about 16 feet. On steeper slopes, 18-20 foot is more practical. However, with the advent of bunker liners, which require hand raking, these dimensions are often not critical.
The capes have some dimensional concerns as well, if machine maintenance is desired. New bank mowers can generally go forward and reverse so unless the superintendent needs to mow with older equipment there is no turning radius to consider with modern equipment. However, these mowers are usually at least five feet wide, and may not be able to mow a narrower finger of turf. At that point, I have the decision to make – why not use an ultra narrow turf finger if it must be hand mowed? That can be a great look.
Visibility
I like my bunkers to be visible, as most do. Why buy all that sand to hide it away? For that matter, on a cape and bay bunker, I prefer it look like a cape and bay bunker, rather than a series of unconnected pot bunkers, which can happen if the capes come too far down to the bottom of the bunker.
Unless you are playing from a highly elevated position – at least 20 foot higher than the bunker - building visible bunkers require that their back be higher than their front. The bottom nose of the cape must usually be a foot higher than the front of the bunker, and the upper end of the bays will vary in height. Making these capes visible is usually the hardest part.
I usually keep a simple front bunker edge, since building up any mounds, ridges, or other landforms simply hides what is behind, or requires me to build it even higher, and usually steeper. Some think that a simple bunker edge front is fairer, since there is no chance that similar shots could have different results – i.e. one shot in sand and the other in the rough.
Bunker slopes can cause all sorts of maintenance problems, and its best to keep them as flat as possible while creating visibility. I have found that the base bunker slope can be up to 15% (7:1 ratio) without significant washing in anything short of a hurricane type rain. With rainy climates and certain types of sand, a flatter base slope from 5-10% (and following natural ground contour) may be better.
I build most bunkers at least a foot deep from the front edge, with a 4:1 slope to kick balls away from what would be the back lip for golfers. (4:1 seems to be the maximum slope most sands will hold on most days, and these will wash in most rains, but are necessary to keep balls from right under the lip on both sides of the bunker) The low spot, where it transitions from the down slope back to the up slope seems to require six feet. Then, to get back up the two feet necessary for visibility requires 7-15 for the first foot to foot and a half and at least 4 feet for the last foot around the lip, and preferably 14 or more.
Thus, for any bunker generally facing the golfer, minimum width is:
4-6 feet for the drop from the front lip
6 foot concave bunker bottom
11-19 upslope to bottom of cape
21-31 feet total at the narrowest point, on the golfers sight line.
Flying into New York, I noticed that many bunkers on classic courses were much deeper than we presume, and much deeper than most golf course architects depict on their plans, and they are usually nicely visible. The bunkers in Adams A example are far more likely to be visible than the B bunkers. However, in both cases each bunker would have to have its base a few feet above the top of the bunker in front, to make them all visible.