Lobster Boat Engine Box Field Report
Three Hundred Traps in the Water, and a Pump I Could Touch But Could Not Turn.
June 3, 2026 · 9 min read
The tide does not wait for a mechanic. Neither does the run.
A marine mechanic in July is harder to find than a parking spot at the wharf. I learned that the hard way, on my knees in the bilge, with three hundred traps still in the water and a raw water pump I could reach with two fingers and could not get a wrench around.
I am not a mechanic and I am not selling anything. I am a sixty three year old lobsterman who has run the same thirty six foot Beal boat my father built, with the same Cummins in her, for most of my life. I do my own work because out here you either fix the iron yourself or you watch the rest of the fleet haul from the dock.
I am writing this for every man who fishes his own boat and has ever sat on the engine box at three in the morning, knuckles bleeding, the season closing on him, beat by one bolt he could not reach. Because a wharf mechanic everyone calls Old Donnie handed me the answer, and he told me to pass it on.
Why a twenty minute job turns into a lost week
If you run a diesel inboard, you already know the engine box. The builder dropped a Cummins or a Detroit into a trough barely bigger than the block, packed in tight between the glassed-in stringers, with the hull on one side and the fuel tank on the other. On paper there is room. Lying on your stomach in the bilge with a flashlight in your teeth, there is none.
The raw water pump is the one that gets you. On a 6BTA the Sherwood pump sits low on the block, shrouded by the starboard engine mount, with less than two inches of clearance between the cover screws and the stringer. You cannot get a ratchet square on it. A screwdriver will not go in straight. So you reach in blind with a stubby, it slips, and it rounds off the soft brass screw. The bolt is not the problem. The clearance is the problem.
I tried everything in the box. Here is what each one did.
- Stubby screwdriver. Could not get in straight, slipped, and stripped the brass slot on the bottom cover screw.
- Standard ratchet. No swing arc between the pump and the stringer. It would not finish a turn.
- Flex-head ratchet. Bent in behind the mount, then folded the instant I leaned on it. The flex joint is the weak point.
- Swivel socket and a u-joint. Deflected off-axis under load and rounded the head.
- The mobile mechanic. Wanted two hundred and fifty dollars just to drive to the slip, and could not come for a month.
A two hundred dollar pump that costs you a whole week
Here is the part that keeps a captain up at night. The pump and the impeller are not expensive. The mechanic is. A mobile marine tech runs a hundred and twenty to two hundred dollars an hour, plus a dock call-out fee, and in July every one of them is booked solid for six weeks because they would rather bill the yacht crowd double. But none of that is the real cost. The real cost is the run. Every day my boat sits tied to the wharf with a dead pump is three thousand five hundred dollars in lobster I did not haul, bait gone bad, and a sternman I still have to pay. You can afford to buy the boat. You cannot always afford to own it.
So I sat down in the bilge that afternoon, cold salt water soaking through my knees, looking at a pump I could touch and could not turn, and I dropped the one good screw I had left straight down into the oily black water under the oil pan. I sat up on the engine box and I will admit it, I about gave up on the boat my father built me. My wife came down the ladder with a sandwich and did not say a word. She has been married to a fisherman long enough to read a man's face.
Two inches of clearance, a soft brass screw, and the bilge waiting underneath for whatever you drop.
Then an old wharf mechanic handed me a bar
That evening I walked down to the wharf to clear my head, and Old Donnie was there, same as always, working out of the tailgate of his truck. He has been turning wrenches on this fleet since the sixties. I told him about the pump and the stripped screw and the two hundred and fifty dollar call-out and the month wait. He did not laugh. He reached into a greasy wood box and pulled out a flat steel bar he had welded up himself, years ago, square drives on both ends, a bend in the middle.
He had me press the drive end. Something moved inside it. A roller chain, sealed in the steel. "I made mine out of an old wrench and a length of chain," he said. "Some outfit finally builds a proper one now. The chain carries the turn around the bend and keeps it dead square, so you come at that pump screw from the side and never round it. Get the real one. Do not buy the cheap ones."
"The chain takes the bend for you."
A slim half inch bar slides flat into the two inch gap behind the engine mount where nothing else fits. The sealed chain carries the torque around the bend, dead square on the bolt, so it never folds like a flex-head or walks like a u-joint. It is called the Savary offset wrench, and it is the bar Donnie spent thirty years trying to build by hand.
The sealed chain is the trick
A roller chain inside the steel body carries torque around the bend, so it never folds like a flex-head or walks like a u-joint.
Slides into the gap
A slim half-inch-thick bar slips into the two inch space behind the engine mount where no ratchet can swing.
Your own sockets
Square drive on both ends takes the sockets already in your box. Holds real torque, up to a hundred and fifty foot pounds.
It reaches. It is honest.
This solves access to a bolt you cannot get a tool on. It is the right shape for the bilge, not a miracle for a fastener already seized to nothing.
It only comes from one place
You will not find it at the parts counter and you will not find it on Amazon. The maker sells direct from their own site only. Eighty nine dollars, shipped to your door. That is less than one hour of a marine mechanic, and a small fraction of a single lost day on the water, for the one tool that hands you back the jobs that strand a boat at the dock.
What happened next
Other men who fish their own boats
"Pulled the Sherwood cover screws behind the starboard mount without dropping one in the bilge. First time in fifteen years I did not have to jack the engine to do it. Two pulls and they were loose."
"Got a wrench on the top starter bolt on the old Jimmy without cutting one in half and welding it like I did in '04. Slid right in past the stringer. Should have had this twenty years ago."
"Bought a cheap chain one off Amazon first. It snapped behind the heat exchanger the first real pull, just like the guys said. The real one does not flex. Night and day."
Donnie learned it the hard way and built his own. Now there is a proper one, and he is passing it on.
Get yours before the run
If you fish your own boat, and you have ever lain in a cold bilge staring at a bolt you could see and could not turn while the season closed on you, you already know exactly what this is worth.
Downeast Field Notes is a reader-supported publication. This is a first-person account from a commercial fisherman and reflects his personal experience. The Savary offset extension wrench is a hand tool designed to reach fasteners in tight, blind locations. It improves access; it is not represented as a remedy for fasteners that are corroded or seized beyond normal service. Always follow proper service procedures and torque specifications. Results vary by vessel and condition.
