SAIL - - Features - — Bradley Con­nor, San Diego, CA

Self-tack­ers, ra­dio trou­ble and diesel ver­sus gas en­gines


Q: I’m see­ing more and more self-tack­ing jibs out on the wa­ter (and in the pages of SAIL) th­ese days. I can’t help think­ing th­ese boats are all hope­lessly un­der­pow­ered, es­pe­cially off the wind, when com­pared to boats with even slightly over­lap­ping head­sails. But I could be wrong. How much ex­tra power do you get from an over­lap­ping head­sail (as op­posed to, say, a 150 per­cent genoa) com­pared to a typ­i­cal self-tacker?


When a yacht de­signer comes up with the sailplan for a de­sign he/she has a cer­tain amount of sail area that can be in­cor­po­rated based on the right­ing mo­ment of the boat. In the past, there was a feel­ing that a big head­sail and a small main­sail was the way to go, in part be­cause main­sails were a pain to deal with. How­ever, as hard­ware changed and main­sails be­came eas­ier to man­age, de­sign­ers found that it was bet­ter to con­cen­trate the sail area there rather than the head­sail. They there­fore in­creased the sail area of the main­sail and moved the mast for­ward to keep the cen­ter of ef­fort (CE) in the cor­rect place. The net re­sult is that you have the same sail area as be­fore only dis­trib­uted dif­fer­ently, so no, the boats are not un­der­pow­ered. Also, ex­cept in all but the light­est of con­di­tions, overlap is over­rated. The 50 per­cent that wraps back around aft of the mast only causes the boat to heel once the wind comes up. Self-tack­ing jibs also more than pay for them­selves in terms con­ve­nience.

MORE ON ‘HARD-WORK­ING’ DIESELS Q: I have al­ways heard that diesels op­er­ate best un­der mid-to-high op­er­at­ing load, like be­ing run for long pe­ri­ods of time and that this pro­vides the best miles per tank, some­thing that is es­pe­cially ap­pre­ci­ated by sailors who do se­ri­ous cruis­ing. That said, liv­ing on Long Is­land Sound it ap­pears to me that very many, if not most of the sail­boats I see are used for Wed­nes­day night/Sun­day af­ter­noon one-de­sign or PHRF rac­ing, or ba­sic day­sail­ing. The reg­u­lar drill for en­gines on th­ese boats is to be started at their slip or moor­ing and run at rel­a­tively low rpms for 10 to 15 min­utes be­fore be­ing shut off for sail­ing—which begs the ques­tion: if so many peo­ple with sail­boats, old and new, op­er­ate them in ways that are in­ef­fi­cient for diesel en­gines, why are there no op­tions to power a sail­boat with an ef­fi­cient, sta­teof-the-art ga­so­line in­board aux­il­iary? I would think that some­one would see an op­por­tu­nity to mar­ket smaller, more ef­fi­cient ga­so­line aux­il­iary en­gines to the sail­ing com­mu­nity. Or do diesels like and ex­cel at light work as well? — Peter Bigelow, Darien, CT


The lauded pen­chant of diesel en­gines for hard work has al­ways struck me as more in­ter­est­ing than im­por­tant: not un­like know­ing that re­frig­er­a­tors are more ef­fi­cient when full, or that lead-acid bat­ter­ies last longer if you don’t dis­charge them deeply. The real al­ways takes prece­dence over the ideal. Diesel en­gines are by de­sign more ro­bust be­cause they op­er­ate at high com­pres­sion lev­els. Even un­der light load this makes them longer-last­ing. They are also more re­li­able due to the ab­sence of electrics and tend to de­velop peak power at lower speeds, mak­ing them a good match for turn­ing a prop. Be­yond that, the ele­phant in the room re­mains the volatil­ity of ga­so­line. A diesel leak in­side the boat is an en­vi­ron­men­tal is­sue. A ga­so­line leak has tragic po­ten­tial for both boat and crew. Re­cur­rent news sto­ries of boat ex­plo­sions al­most in­vari­ably in­volve ga­so­line. Rarely are sail­boats in­volved, be­cause so few now carry ga­so­line in in­ter­nal tanks. The pru­dent sailor even stores ga­so­line for the ten­der out­board on deck. With the ready avail­abil­ity of light­weight diesel en­gines, the choice to­day to re­tain ga­so­line power is al­most al­ways driven ei­ther by cost, com­pli­ca­tion or a de­sire to main­tain orig­i­nal­ity. As for in­board ga­so­line power for all other sailors, I’m pretty con­fi­dent the ver­dict is al­ready in.


Q: My 1982 7.5hp Ev­in­rude out­board fried my new AGM bat­tery in two years. I saw the volt­age at 15.1 volts most of the time. I since have in­stalled two diodes in se­ries in the charg­ing line. I also added two switches in par­al­lel to each diode. I start the day mo­tor­ing with both switches open, but as the bat­tery charges I close one switch first, then af­ter the bat­tery charges more I open the sec­ond. I al­ways stop the mo­tor be­fore mak­ing the switch. Do you think it would be OK to change the switches with the mo­tor run­ning?


Prob­lems arise when you dis­con­nect or oth­er­wise switch off the out­put cable from an al­ter­na­tor while it is run­ning. There is a volt­age spike that can de­stroy the diodes in the back of the al­ter­na­tor. How­ever, in your case the al­ter­na­tor re­mains con­nected to the bat­ter­ies at all times. So yes, I am pretty sure you will have no prob­lems open­ing the switches with the mo­tor run­ning. That said, I would run with one of the switches open at all times. As­sum­ing this im­poses a volt­age drop of around 0.6 volt, it will drop the volt­age at the bat­tery to 14.5 volts, which is about where you want to be in terms of the ab­sorp­tion volt­age, with no risk of ac­ci­den­tally driv­ing the bat­tery higher. When the bat­tery is fully charged, open­ing the sec­ond switch will drop the volt­age to a lit­tle be­low 14.0 volts, which is about where you want to be for a float volt­age. Note that to make sure th­ese are the kinds of volt- ages the bat­tery is see­ing, you need to test the volt­age across the bat­tery posts as op­posed to any­where else in the sys­tem.


Q: On week­ends, I am ad­dicted to my trusty AM ra­dio for the ball games now that foot­ball is back. I re­cently in­stalled a new marine au­dio sys­tem, and it works great for the me­dia I plug in. It also works fairly well on the FM mu­sic clas­si­cal sta­tions my wife loves. How­ever, for AM sta­tions I have lit­er­ally no re­cep­tion, even though I am us­ing my marine VHF mast­head an­tenna up 40ft off the wa­ter. What gives?


Sounds like you are us­ing an en­ter­tain­ment ra­dio an­tenna split­ter to the VHF an­tenna. While split­ters for AIS may work on a mast­head VHF an­tenna, you can­not rely on th­ese split­ters to work at all on broad­cast band AM on a marine VHF an­tenna. Most mast­head VHF an­ten­nas have a coil “shunt fed” to mast ground, and at AM broad­cast ra­dio fre­quen­cies your sig­nal is grounded to­tally out. The cheap no-name split­ters are not a good match to your life­sav­ing VHF marine ra­dio ei­ther. Ditch the AM/FM broad­cast ra­dio an­tenna split­ter and go to a lo­cal auto store for a rub­ber re­place­ment whip an­tenna and cable. Plug in the cable end to your marine stereo and en­joy both im­proved FM and loud-and-clear AM ra­dio ball games. Hide the whip any­where be­lowdecks for best re­cep­tion.

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