Do not go for a very high mast, as, unless you ballast the boat, it will 

Rig the mast like most sailboats, that is, put a spreader bar about 2/3 

Rig the boom so that it can be hoisted to and secured in a vertical 

If the new mast height will add additional problems, you can step the 

Any sail rig on a power boat not designed for it will, at best, be a 

Bob and All, Just thinking out loud....... Bob, you didn't say if you want to put a boom on the new mast, so I will assume you do. First, precautions: When you put a mast with a boom and sail on any boat that has not had one that was used with a sail, you have to make sure that the deck/cabintop or whatever you step it onto is capable of handling the compression loads that a mast can generate. This is not just the deadweight of the mast, boom, sail, radar, antennas, guy wires/rigging and such, but also the forces created by the sail. The bigger the sail the more force for a given wind. Also, the standing rigging/shroud/guy attachment points on the boat must be able to withstand the load while remaining water/weatherproof, i.e., they don't work loose and break the seal, thus allowing water into the boat. Do not go for a very high mast, as, unless you ballast the boat, it will be quite tender (tippy) in any wind if the sail is up. Also, remember the mast and weight aloft becomes a pendulum. Use as long a boom as is aesthetically possible. This will move the center of pressure as far aft as possible (assuming you are not trying to use the sail for anything other than steadying the boat while under way or to prevent the boat from "sailing" when at anchor) while giving you a long arm to reach out over the edge of the deck to lift things from the dock or water. At any rate, make sure the center of pressure on the sail is aft of your center of lateral resistance for the boat relative to the water, i.e., make sure the boat will turn into the wind if a strong gust hits it when the sail is up. Assuming the underlying structure can carry the load: Rig the mast like most sailboats, that is, put a spreader bar about 2/3 of the way up the mast (or, at least about 7 feet up, giving clearance to walk under it) and bring the shrouds down to the gunnels. This will give you walking room (as the spreaders will push the shrouds out so they drop almost vertically to the deck and even provide a handhold on each side of the boat. If you carefully calculate the loads (get a marine architect to do this who has experience with sailboats) you can get away with having only 3 guys on the mast, they are supposedly placed approximately 120 degrees apart, but the aft two can be moved forward quite a bit, as long as the sail area/windloads are carefully calculated. To envision this, look at any sailboat with a mizzen mast. Rig the boom so that it can be hoisted to and secured in a vertical position when not in use. This will give you space to enjoy lounging or a place to store stuff (dinghy) aft of the mast. To envision this, look at a large sailboat equipped with downwind poles which are permanently mounted on the mast and stored in a vertical position. You can leave a steadying sail mounted on the boom if you have a tight cover over it to reduce windage as well as prevent sun damage to the sail. If possible, make the boom long enough to extend past the edge of the hull when laid over against the shrouds. This will allow you to put a block on the bottom of the boom and use it to haul things aboard from a dock or the water. The topping lift (cable assembly used to hold the boom up) and shrouds must be strong enough to carry the weight of the boom, wet sail, and any other load you impose on it when using the boom/mast as a crane. Boom control could be most easily provided by using a split block and tackle arrangement using two pad-eyes attached on the cabin-top, one on each side. Run the control line from the mast to the block on the boom, then down to a block on one pad-eye, up to the block on the boom, down to another block on the other pad-eye and back up to the block on the boom where it is attached. A better setup would use two block and tackles, each going from the boom to one of the pad-eyes. This would permit the boom to be pulled down tightly to flatten the sail when using it as a riding sail when at anchor. It is best if the boom cannot move from side to side. Use snatch blocks on the pad-eyes to allow easy removal when storing the boom vertically. Variations on the theme: If the new mast height will add additional problems, you can step the mast using a tabernacle. That is a special base that, while supporting the mast, will allow you to lower the mast to clear bridges, etc. Set it up so that the mast drops aft, so that your radar antenna would be protected by being on top of the mast when in the "down" position. The tabernacle can be made so that it is quite high, say 5-6' at the top, but with the hinge pin at the bottom. (A cut-out section of larger sail mast would work for this purpose.) This would give you a lever arm to raise and lower the mast, using a small trailer-type winch. The forward shroud/guy should have a quick release connection to facilitate this. To envision a tabernacle of this type, ask an amateur radio operator to show you a picture of a ham antenna made this way. They are usually called "self raising" and are fairly common. Another word of caution: If you use a tabernacle of this type, all the load of the mast when raising or lowering it will be on the tabernacle base; so a temporary forward guy on the tabernacle is recommended. This could be a simple cable assembly such as is used on sailboat lifeline gates. General thoughts: Any sail rig on a power boat not designed for it will, at best, be a compromise. If well thought out, designed and built, on a boat that is capable of handling it, there should be a positive net gain in the utility/comfort of the boat, provided all safety considerations are made, such as a means of quickly dumping the sail if need be. On the other hand, it could make the boat very unstable as well as damage it by imposing loads in places that were not designed for them. Any modifications of this sort should be designed by a competent marine architect/engineer. I would never recommend someone inexperienced with sailboats attempt this on a power boat without first seeking competent advice relative to his specific boat. Wayne M/V Celestial Albin 43 Sundeck