Bill Shaw Answers The Mail - The Pearson Current - Volume 1, #3

BILL SHAW ANSWERS THE MAIL
The Pearson Current - Volume 1, #3 - 1994

I sail a 1978 Pearson 31, on Lake Michigan. The Bill Shaw design was conceived as a racer-cruiser and though this purpose was beautifully executed in my view, evidently the boat didn’t meet expectations, as production stopped after only two years in 1979.

It’s a great boat and I’ve been very pleased with her performance except to windward as she routinely tacks through 110°. The headsail blocks attach at the toerail yielding a 14° jib lead angle. I’ve always assumed she was meant to have inboard tracks. Copies of original drawings only show optional genoa tracks on the coamings (way back for even my 155%) but no inboard jib tracks. I’ve been tempted many times to put down inboard tracks and bring the lead angle down to 9°–10° but I’m afraid of damaging the cored deck under load. As there were few P31’s of this vintage built, I’ve never seen another so I haven’t been able to confirm if inboard tracks were just somehow omitted on my P31. Any insights would be greatly appreciated. — Craig & Norma Jean Juel Valparaiso, IN

Dear Craig & Norma Jean, You are right, the P31 did not stay in production past 1978 ending in that year with hull number 65. The version of the 31 that you own was considerably different than the one that was produced from 1986 through 1990. Your P31 was designed to capture a market demand for IOR class racing. Being both a masthead and 7/8 rig, the boat had limited appeal to the general market due to the relatively small cockpit design. The P31 was redesigned in 1979 to enlarge the cockpit thereby forgoing the IOR designation.

If you inspect below the deck behind your lockers where the inboard jib track would naturally fit you might find indication of extra support molded into the deck to accommodate the deck gear. If this is not evident, you could still install a jib track if you also include additional support in the form of a suitable backing plate. This should be made of SS 3/16" thick with bolt holes matching the track holes.

Regarding the actual use of an inboard track, it’s best used for light air and up wind sheeting. When the wind is about 15kts or more over the deck or with a nasty slop, shift to the outboard track.

We are trying to find out the history of the P37. How many were built? When did they stop building them? Is this boat OK for cruising? Does this boat have any quirks we should know about? What is the Baby stay for? How do we use it? How do we use the hydraulic backstay and boom vang for maximum effectiveness when under sail — both in high wind and under light air? What jibs should we use for effective sailing and maximum speed? What determines when it is best suited to reef the main, and approximate wind velocity for the first reef and then also for the second reef? Would it be possible to hear from other P37 owners? We have a lot to learn about the boat. It is a beautiful boat and we are proud of her. — Terry and Jeanie Tornow Savinaw, Texas

Dear Terry & Jeanie, Your P37 was also an IOR design, produced from 1981 through 1983, hull number 42 was the last one produced. This boat has the distinction of having twice won the Boat of the Year in the Gulf of Maine series. As a solid, well-built boat, the P37’s racing orientation does not preclude its ability to handle off shore seas. What constitutes a cruising over a racing boat is very often a personal decision. Can this boat handle blue water? Most assuredly. However, the IOR did impose design restrictions that might make the boat less attractive to those looking for a more traditional or dedicated cruising design. Only you can make that decision which typically turns out to be based on comfort — however that factor might be defined by you and your crew.

In response to whether the boat has any "quirks," I am not aware of any nor have we received any comments that would lead us to flag the boat.

A baby stay is used to control mast bend. With a baby stay you can flatten your main more in heavy weather which should help increase speed. A drawback to the baby shroud is in jibing your spinnaker. The shroud will get in the way of your pole and adjustments to accomplish the maneuver will be necessary.

Regarding your question on the hydraulic backstay and the boom vang, you must be very careful not to put too much strain on your rigging. Most manufacturers will not warrantee a boat with an hydraulic backstay, for you can easily do serious damage to both the hull and the rigging if you do not watch what you are doing. A general rule recommended by most builders is that the strain not be more than ¼ of the breaking strength of the stay. For instance, a ¼" stainless steel 1x19 wire has a breaking point at 8,400 pounds which puts the maximum acceptable strain at 2,100 pounds.

As to what jibs to use — you should work closely with a local sailmaker. Inform him or her of the type of sailing you do, normal crew size and their experience. A responsive sailmaker will spend some time with you on your boat and put together a sail inventory that will meet your needs and maximize the performance of your boat as it relates to your region and sailing conditions.

I recently repowered my 1972 Pearson 30 with a Yamar 18 HP 2 cylinder diesel engine. I am still unsure whether I have the best size propeller. The yard recommended a 3 blade 14" diameter by 8" pitch. I tried this size propeller for a season and felt the boat didn’t have quite the driving power as the old Atomic 4 with its 2 blade prop.

Over the winter I had the pitch changed from 14x8 to 14x9. Based on limited seatrials, the boat seems to drive through an oncoming sea much better.

I know that using a 3 bladed prop is costing me some speed under sail when compared to a 2 bladed prop. Is there some rule of thumb that states how much speed is lost when sailing with a 3 blade as compared to a 2 blade? Has a tabulation ever been made that compares 3 bladed props to equivalent 2 bladed props? How much more pitch do you need on a 2 blade to match a 3 blade prop while keeping a constant diameter? If I am happy with the performance of a 3 blade 14x9 prop under power, can I find an equivalent 2 blade prop that will be compatible with the engine specifications? Bear in mind that the diameter can not exceed 14 inches. — George Taylor Waltham, MA

Dear George, Arguably the most difficult boating questions to address involve the specifics of propellers. Volumes have been written and the controversies that surrounds each decision has become legendary. The right prop to use is a function of several factors starting with engine horse power, shaft RPM and boat speed. Hull and bottom condition and actual displacement also play a crucial role.

The science exists to accurately design a proper propeller. It’s done all the time with good results. However, it is paramount that the data be very accurate. For example, in addition to the manufacturers information on engine horsepower, the relationship between RPM, HP and actual boat speed must be determined. A mechanical tach or better yet, a strobe tach is needed to measure these relationships. You can’t rely on the tach in the instrument panel. The boat speed through the water must be obtained using a measured mile by calculating the speed in both directions, up current or wind and then the reverse. You must then average the calculated speeds of the boat and not the times.

We don’t mean to be unnecessarily complicated, but the reality is that propeller decisions are as technical as any issue facing boat manufacturers and they need to be carefully considered for optimal performance. Your questions are best handled by a naval architect and we recommend that you call Bill Richards at 401- 254-0775. Bill offers discounts to NPYOA members and is familiar with Pearson boats, having been a manager for the company.

Topics for the newsletter: How can we stop internal mast noise and water infiltration via the sail track in keel stepped masts? Why is "pre-1984" mentioned when discussing parts availability? — Joseph Weinbrecht Stockton, NJ

Dear Joseph, Running halyards inside the mast clearly cleans up the spaghetti aloft but on the downside, it is much more difficult to keep the lines quiet for they tend to rattle around within the mast no matter how much we tighten them up. Using extra low stretch lines does help but will not eliminate the problem totally. You might try going the other way and leave them very loose. If you do, be sure to protect the standing part of the lines from chafing against spreaders, shrouds, etc. We are not sure what you mean by water infiltration. Is the water seeping below deck or into the mast itself

We cut off parts availability at 1984 because rights to the Pearson name & parts after 1984 are owned by the Aqua Bouy Company.