Towing a 15-foot Whaler astern of a single engine trawler is a couple of quantum leaps up the chain from an eleven-foot Whaler. I offer the following food for thought to anybody towing dinghies: Lesson 1: I once had a 13-foot Whaler with 25HP outboard break loose from the cabin top of a 60' Chris Craft Roamer I was delivering. The heavy seas caused it to flop dangerously around from the swinging davit at the end of its hoist wire, I quickly lowered it into the water and towed it for another 400 miles. I used a stainless snap shackle to attach the towline to its bow eye. By the time we got into port, the bow eye was severely chewed up by that stainless shackle, and the towline was pretty far gone. PLUS I had to worry 24/7 about possibly flipping the darned thing in heavy seas. Had that happened, we (the owner and I) had already decided that due to a host of other considerations, we'd abandon it. Lesson 2: I towed a 23-foot Mako with twin outboards to the Bahamas across the Gulf Stream one night behind a heavy 65-foot converted head boat powered with twin 671 Detroits. The trip went ok, but I was always looking astern all night long thinking it would be fun to try to find it even after only a few minutes lag time between its departure and my discovering same. We lost a knot. That same boat once had its towline get caught in the gate of a lock in the cross-Florida waterway system that goes through the Lake Okeechobee - I wasn't there that time. Lesson 3: With my twin 120 Lehman 42-foot Grand Banks, I towed a 13' Whaler with 50HP Johnson which also had power tilt at trim (total around 5-600 pounds). We enjoyed the convenience of the Whaler when on the hook, but the hassle with towing it by land to launch it, getting it over to the trawler, getting clear of whatever slip I was in with it, worrying over it security as it was towed, returning it to its trailer when cruise complete, etc, etc, etc, was simply detracting from the overall joy of the cruise - I sold it. It slowed me about one half knot. I suspect you, with a single 120-Lehman, may lose upwards of a full knot towing a 15-footer with its fuel and engine plus whatever else may be in it. Current set up from lessons learned: My current dinghy is only a 10-foot inflatable with inflating keel and a 9.8HP outboard. It is SECURELY fastened to the cabin top where I do not have to worry about it underway in a thunderstorm or when entering locks, marinas, slips, etc. It's no Whaler with all the increased passenger security inherent there, but I enjoy the trawler/dinghy combo more this way than when towing something too heavy and awkward to hoist safely aboard. Other experience: I have been the Commanding Officer of a large Navy single screw oceangoing towing and salvage ship (205 feet, 1600 tons, 69-man crew). I have towed stuff a long ways over oceans, and long tows come with a host of issues and contingencies that cause professionals to go to great lengths to prepare for. Amusing story: Friends were towing their soft-bottomed dinghy across a major expanse of the South Pacific when they noted that it had become f=more sea anchor than dinghy. They found a couple of PERFECTLY round several inch holes in its bottom. You may find the maker of the holes here: http://www.enchantedlearning.com/subjects/sharks/classroom/sharktemplate s/Cookiecutter.shtml Suggested mitigation: If you insist on towing a valuable piece of property around at the end of a fiber line over long distances behind a single-screw trawler, I'd suggest taking some ordinary precautions some of which are prevalent in the professional towing world: Tow in daylight as much as possible. After you have estimated the required fitting and towline strengths required, double them. Have the tow well lighted so you can find it at night. Regardless of above, always have somebody with a searchlight handy to illuminate it at night when in the vicinity of other vessels. Put a radar reflector in the tow. Don't tow in conditions in which you could not recover the tow if it breaks loose. Tow a retrieving line (attached to the bow of the towed vessel) with a float trailing astern of the tow so you can maneuver to pick it up with a boat hook without having to put a person in danger. Attach a chem-light to the retrieving line's float at night. Get one of those dinghy alarms that sounds a warning when the tow line breaks. Attach a second towline a few feet longer that the primary to another attachment point on the towed and towing vessels. Attach a line cutter to your one and only propeller shaft for the time you suddenly must stop regardless of the fact that you have a heavy Whaler about to smack your stern and foul your prop with its towline. Speaking of big dinghies and trawlers, I once saw a 36-40 foot trawler at our local marina's transient pier with a 13-foot Whaler aboard. It was stowed aboard fore and aft a bit to starboard of centerline with most of its forward section sitting over the aft cabin's top. The stern projected a little aft of the taffrail and was supported by a beefy gallows built on deck just forward of the taffrail. One could get from one side of the stern to the other by going under the Whaler's bottom, about waist high. I would imagine the lifting rig was powered and hopefully (probably not) properly weight tested. I didn't suggest not towing the 15-foot Whaler you contemplate (you may have a real need to do this); nor do I advocate putting something even as large as a 13-foot Whaler aboard a trawler of less than about 50 feet. I personally would not, except for something like a day trip to and from our local barrier island, tow a dinghy of ANY kind, and I have line cutters. Rich Gano CALYPSO (GB42-295) Southport, FL