Installing the Speedseal impeller cover is one of those boat improvements you only appreciate once a year – or when something goes very wrong.

Speedseals are replacement plates to house your engine's impeller, the bladed rubber cylinder that pulls in sea water to cool the plant. Without a well-working impeller, the pump struggles to get cooling water. Without cooling water, the engine overheats. The cautious captain will change the impeller seasonally – and that is never an easy task.

SpeedsealThe basic Speedseal in a plate of naval brass with an inset O-ring, which replaces your existing impeller cover. Stainless steel handscrews make changing the impeller easier.

Impellers are notoriously devilish to deal with. They are often located in hard-to-reach places, necessitating yoga-like contortions and only very tiniest of tools. The plate guarding the impeller is invariably protected by half a dozen baked-on bolts. And if you can reach the thing and open the plate, extracting the impeller is like pulling a conch from its shell. The cure for a sick impeller is replacement, so imagine doing all of that in even a moderate sea.

The answer is Speedseal, a machined, ¼-inch naval brass plate with an O-ring set into a machined channel. The whole thing replaces your engine's factory plate, and is attached with large handscrews made of marine-grade stainless steel, which are easy to manipulate without tools. Two of the screws fit into U-shaped slots on the seal, rather than holes, insuring that the plate is self-aligning and can be re-seated even if you cannot see well.

The Speedseal is one of those great safety improvements that you can make for less than $100 and one hour of your time. They have been around for years and have been blessed by an armada of boating magazines, including Practical Sailor and PassageMaker. Best of all, this is truly a project you can do yourself.

LEAVE THE MECHANIC HOME

It starts by taking a look at your impeller pump to see the configuration on the stock plate. Check the manual to find the pump, or simply run back your cooling line from the seacock. The factory plate may have three, four or six bolts, and Speedseal makes models to accommodate each (you will have to specify when ordering).

SpeedsealAbove, the Speedseal has U-shaped slots that make the plate it easier to seat, especially when you cannot see. Below, large handscrews make the plate easy to tighten, without fumbling with tools.
Speedseal

I was preparing for a trip for Maryland to New to New York when I installed my Speedseal. My Yanmar 370 has a four-bolt plate, placed so far to port it is almost in the bilge and hidden by a massive wire harness. At 6-foot-1 and 250 pounds, I practically needed hydraulics to get into the proper position (and a crane to get out). Getting the harness out of the way required a wire tie and fighting the bolts had to be done with a stubby wrench. Installing the Speedseal seemed like a smart investment.

I chose a day when the mechanic was on board, just in case I badly fouled something up, but the supervision was unnecessary. This was easy stuff. I closed the seacock and battled the bolts. Naturally, some water from the line flowed out. I saved the factory plate and bolts and bagged them as spares, then pulled the impeller with a palm-sized vice grip I had in my bag. I have two different impeller tools on board, but the mechanic insisted the tiny wrench would work better. I have read many horror stories about impellers being mangled by wrench-wielding boat owners, but I yielded to his wisdom. It came out intact.

I handed it to the mechanic, who said it was good. No nicks, tears or other signs of wear. I concurred and popped it back in, making sure the blades were set in the proper direction (look before you take it out). On went the Speedseal. I set two screws, seated the plate and then fixed the other two screws, hand tightening each. The manufacturer recommends against tightening them with a wrench, noting that the back pressure on the seal and plate helps lock the handscrews.

WAS THAT IT?

And"¦that was it. The seal was pre-fitted into the plate. The plate was easy to seat. The screws were easy to tighten. I was done. I contorted myself out of the hole and the mechanic laughed at me. But it was a kind-hearted laugh. He knew he might be the one contorting next time.

When it comes to safety, Speedseals are a no brainer. The plate, seal and screws cost about $83 at the current conversion rates (Speedseal is a British company) and another $8 for shipping, which takes about a week. It comes with a free impeller removal tool.

A pack of spare O-rings costs about $12 and a package of two extra screws sells for roughly $9. I bought both. If you carry a spare impeller – and we all should – why not carry spare bolts and rings. For about $12, they also sell the impeller tool and a three tubes of silicon grease, which can be used to coat the impeller's drive shaft to make it slide out more easily. Ordering information can be found on the Speedseal web site (see link below), and be prepared to specify the make and model of your engine and pump.

Pricing on the Speedseal may seem steep for something you cannot play with, or even see most of the time. But I'd rather pay now than contort later, especially in 6 foot seas and 30 knots. For any long passage, I'd consider them a necessity. In fact, I want one for my generator too.