How To Improve Your Prop Performance

Check other factors before you blame the prop. Here’s how to improve your prop performance.

When a boat runs poorly, propellers often get blamed. If the engines are in good shape, it’s only natural to get “propeller tunnel vision” and start indicting your blades for not doing their job. Before you yank out the prop puller and start trying new wheels, remember that props must work in harmony with the rest of the boat. If other parts of the vessel are not in top shape, then the prop can’t save it.

“Some people seem to view the propellers as isolated and independent from other important factors, such as the power and condition of the engine, or the weight, or the cleanliness and capability of the hull,” explains Jim Thelen, sales engineer for Acme Marine in Big Rapids, Michigan. “I’ve seen people buy numerous new propellers as if to assume that sooner or later they will find the one prop in existence which will ‘fix’ all other possible concerns and transform their performance by something outlandish.”

More than just a proppy face

There are some boat owners who take the oversimplified view of propellers merely in terms of diameter, pitch and number of blades. That’s like defining all automobile tires only in terms of diameter and width. Propeller design and manufacturing differences affect engine load, speed, power, plane time, smoothness, and efficiency.

“Some propeller factors which should be accounted for by a professional are the size of the blades or the amount of surface area in the propeller blades (often indicated as DAR or EAR), Cup (which affects load/engine RPM much in the same manner as pitch) and pitch distribution (varied, constant, cambered),” says Thelen. “The point is that one manufacturer’s twenty-by-twenty four blades may not be equivalent to another
manufacturer’s twenty-by-twenty four blades.”

What’s amiss?

The hull’s condition can also significantly affect performance. Thelen describes how one boat’s power and speed relative to published or reported performance was down. “He tested the new propeller I recommended and still, his RPM and speeds were down significantly.”

Thelen went through his usual litany of questions about boat weight, engine service, cleanliness and condition of the hull, possible modifications to the boat, and altitude. Nothing revealed itself until he dug deep enough to get the owner to admit that the boat had been moored in warm ocean water for a long period which resulted in a rough bottom. “It wasn’t until he had the bottom stripped and refinished that he gained the speed he was looking for,” says Thelen. “We had him into the correct propeller from
the start.”

Extra Load

An overweight vessel can also be a problem because, over the years, boats usually get heavier, not lighter. Stuff goes on board every weekend, but not all of it comes off, and it can really add up. When add-ons and enclosures increase wind resistance, or a dirty hull increases flow resistance or when engines get tired, the boat slows down, and the original props can become overpitched. Sometimes you can improve your prop performance by simply chucking some stuff.

“The original props may not be achieving sufficient RPM relative to the engine manufacturer’s RPM ratings,” says Thelen. “The loss of RPM and potential overloading can cause power loss, speed loss, slower plane time, and potential engine damage, especially in terms of long-term use. The most common approach is to reduce propeller pitch in order to achieve appropriate wide-open-throttle RPM.”

To determine if the propeller is working its best, “It’s important to keep an accurate log of one’s boat model and weight, engine model number, manufacturer’s RPM specifications, transmission or V-drive gear ratio, current prop size, etc.,” says Thelen. “Most engine manufacturers place an ID tag on their engines which indicate s horsepower and RPM specifications.

Determining appropriate propellers basically involves running the boat (with typical or average load) at full and verifying that the engines are achieving the expected or recommended RPM at WOT [wide open throttle] and that the boat is achieving reasonable, expected speeds.”

Thelen suggests that if RPM readings are below the manufacturer’s WOT recommendations, then the propellers are likely overloading the engines. If the actual WOT RPM reading is too high, then the propeller is likely underloading the engine and, perhaps, a different propeller can improve speeds.

Data is King

Data and proper care of all facets of your engine can help to improve your prop performance.

But before you start swapping out props, verify all the data: boat weight, engines, gears, current props, speeds achieved. It’s nearly impossible to get a precise propeller answer if the reported data and specifications for the boat are off the cuff, guesstimated or vaguely recalled from several years ago.

“Complete data, accurate numbers, and double-verified specifications can produce very accurate propeller recommendations,” says Thelen. “I urge people to verify all their boat, engine, gear, and current propeller data with their own eyes and to write everything down.”

Thelen advises that having a spare propeller is a good idea. “Most people don’t go very far with their automobile unless they have a spare tire,” he says. “And most people aren’t very happy being without a boat on the first day of their vacation because of a damaged prop.

Furthermore, there are so many different types and sizes of propellers in existence today that no one can carry them all, which means that the waiting time for a replacement, for some props, can be months rather than weeks. So if you like your boat and if you want to be able to continue using it when the surprise moment comes, then I suggest carrying a spare.”

acmemarine.com

By Doug Thompson, Southern Boating May 2019

Annual Haul Out Guide

A Southern Boating Magazine Supplement: Annual Haul Out Guide

Our annual haul out guide has everything you need to know about planning your boat’s maintenance. From new system installation to surprise costs and product reviews, Southern Boating is your number one resource for planning a trip to the yard.

Our annual Haul Out Guide is a reader favorite and now we’re sharing the valuable info.

The 2019 guide covers fire suppression systems, potable water, windlass advice and much more. Read the 2019 articles here, or download the entire guide below.

Below is our archive of printable/downloadable Haul Out Guides. Take it with you to the boatyard, your backyard or wherever you work on your boat.

Questions? Comments? What are your tips and comments about getting work done? Let us know and you could be featured on our website! Tell us your best with your best haul out stories in the comments.

2019

2018
2017

Dock Maintenance

Regular dock maintenance will keep it safe for your boat and guests.

It wouldn’t be wrong to say every boat owner has at least an ounce of pride in their vessel no matter its condition, with most taking great strides to make sure it’s cared for
and in good shape. No one wants to miss the opportunity to get out on the water when the time is right. In addition to keeping the boat up to snuff, the same goes for its home port: the dock.

If you’re lucky enough to own your own dock or even if you rent one, it’s important to maintain the structure and add features that protect both the boat and those who
walk on it.

Inspect it

Safety should always be at the forefront. Each time you walk the dock, look at it with an eye for imperfection. Look for nails or screws backing out of wood planks and for loose and rotting boards. You don’t want the kids or guests to trip and fall or catch splinters in their feet.

Is there anything missing? Take a look at the structure both above and below the waterline. Are fasteners, bolts, nuts, and cross beams solid? When you jerk the dock, does it feel like the pilings are loose? Are lashing straps tight around the floating platform? If you think “I should fix that,” then don’t wait. Plan to do it as soon as possible.

Keep it clean

Besides keeping your dock clear of debris, toys and loose gear, clean it. A stiff scrub brush with biodegradable soap or environmentally safe cleaning solutions like baking soda paste are usually effective, but a pressure washer makes the job easier. Remember that using a pressure washer can “burn” the wood if the spray nozzle is too close. Afterward, the wood will be softer and splinters will appear, so take a sander to the boards and smooth out the rough spots. Also, take time to sand out any rust spots on steel parts or supports.

Don’t forget to remove growth as well. Barnacles and other creatures, as well as plants, cause damage that can’t be seen until they’re removed. A putty knife usually does the trick, but scrub the area with an abrasive pad after removal to make sure.

Fix it

Don’t wait to make repairs. Murphy’s Law will find its way, and covering the dock with carpet or such only hides what will continue to get worse and cost more later. If there are damaged areas in a wood dock, use marine putty or wood filler to repair holes or splits. Replace screws or nails if they’re backing out, and if they are, evaluate if the board needs to be replaced. It doesn’t matter how much the dock is used; hardware will loosen and rust with weather, so regular dock maintenance is important. Lubricate moving pieces such as chains, and replace rusted parts when necessary.

Seal it

Wood docks, in particular, are vulnerable to the marine environment through moisture, sun and changing temperatures, so use only treated lumber. Once the dock is cleaned, repaired and sanded, apply a waterproof sealant that is environmentally friendly. There are sealants available that are low volatile organic compounds (VOC), but check local regulations before applying. If you remove the dock during the winter, allow the sealant to completely dry before installation.

Dress it up

Now that the dock is clean, safe and secure, trim the dock with a few accessories. Protect the boat from accidental bumps by attaching dock bumpers and rub rails. The areas that cause the most damage are the corners, and bumpers come in a variety of configurations and lengths as well as materials. They mount in a number of ways from along the
sides, corners, flush with the top, around pilings, and more.

Another safety feature is to add lights. “Docks and seawalls can be precarious and dangerous areas, and any additional lighting is beneficial for accident prevention,” says
Mick McDonald of Lumitec. “Lighting adds an additional level of security to your property to help protect expensive investments.” Lights also add ambiance to your dock and property and attract marine life to watch on a warm summer evening.

Chances are, your dock is used for a variety of activities as well as a place to store gear. If you inspect it regularly and keep it solid, clean and safe, it’ll be the perfect home for your boat and a great place to hang out for many seasons to come.

By Steve Davis, Southern Boating March 2019

Return to the Haul Out Guide

Maintenance Check

Time for a maintenance check. Don’t skip these oft-forgotten items

There’s a lot of terrestrial-based wisdom that just doesn’t ring true when it comes to boats. “Out of sight, out of mind,” “What you don’t know can’t hurt you” and “Let sleeping dogs lie” are all perfect examples of advice not to heed when planning your boat’s maintenance. In an effort to protect you from old wives and their tales, here are three often neglected items that can ruin your boating day quicker than stepping on a crack can cause you to cry over spilled milk. Just do a maintenance check.

Maintenance Check #1: Anchor rode and connections

No matter what you enjoy doing on the water, there’s one need all boaters have in common: the ability to anchor safely and securely. Unfortunately, the other thing they often have in common is poorly maintained or unserviceable ground tackle.

While the anchor typically enjoys a place of prominence at the bow, the anchor rode is relegated to the dark, dank recesses of the anchor locker. In a nutshell, its purpose is to connect the boat to the anchor.

Most boats use a combination rode, which is simply a rope rode with a length of chain between it and the anchor. The chain protects the rope portion of the rode from chafe along rough seabeds and adds weight that increases horizontal pull and helps the anchor remain set. Three-strand nylon is most commonly used for anchor rode. It’s strong, provides more elasticity than a braided line (which absorb the sudden loads and jerks of a bouncing boat), is more easily spliced, and is less expensive.

Your anchoring system is only as strong as its weakest component, which includes not only the rode, but also shackles, splices, chains, mooring bitts, cleats, and, in short, any gear used to secure your boat while at anchor. Proper maintenance includes inspection of these items as well as pulling the rode from the anchor locker and inspecting it at least annually. Check rope rodes for wear, hard spots, cut strands, aging, discoloration, etc. Chafe is rope’s worst enemy, so you’ll also want to inspect hawseholes, chocks, cleats, and windlasses for burrs, sharp edges or anything else that can cause rope damage.

Maintenance Check #2: Stuffing box

Stuffing boxes (aka packing glands) are victims of their own reliability. They carry on so well with such little attention that many boat owners don’t realize they need regularly scheduled maintenance.

The purpose of the stuffing box is to allow the propeller shaft to exit the hull while keeping water out. The shaft is sealed by compressing packing material against it, most often by using a hollow nut that screws onto the inboard side of the shaft tube or a tightening arrangement that uses a plate secured by nuts and studs on either side of the shaft. The more you tighten either type of gland, the more the packing material gets compressed against the shaft. Most packing consists of a square plaited material and comes either as traditional greased (or waxed) flax or a more modern version impregnated with Teflon.

Water helps lubricate the packing material, so it’s okay for a stuffing box to leak a few drips (three to four per minute) while the vessel is underway. More than that amount (say 10 drops per minute) or any drips while the shaft isn’t turning indicate the need for maintenance. A stuffing box leak can cause everything from corrosion (the spinning shaft slings excess water all over the engine compartment) to sinkings, particularly if the boat is left unattended in the water for long periods of time.

Maintenance Check #3: Packing Material

Packing material hardens over time (as the lubricant dries out) and gets worn away by shaft rotation, allowing water to pass and enter the vessel. When this happens, most boaters simply tighten the packing gland to compress the packing material and stop or reduce the leak. This works to a point; however, as the packing gets smaller, it also gets harder. Keep compressing it, and it will eventually score the propeller shaft, which will then have to be replaced before the stuffing box will seal properly.

The simplest answer here is to replace the packing material on a regular basis. This bit of routine maintenance should only take about 30 minutes and normally costs less for materials than you’d spend on a mocha-frappu-latte-whatever and a free-range muffin. How often you repack typically depends on the number of hours your boat is used. As the vessel has to be hauled, many owners simply repack annually as part of their haul-out or spring commissioning routine.

Maintenance Check #4: Fuel tank fill hose

You’d be hard-pressed to come up with a more out-of-sight, out-of-mind item than your fuel tank fill hose. Fill hoses are attached to the underside of the fuel fill fitting, connecting it to your fuel tank.

All hose has a limited lifespan, and fuel fill hose is no exception. Recommended replacement timeframes will vary between fuel hose manufacturers, but some call for replacement as often as every five years. The American Boat and Yacht Council standards also call for flexible fuel fill hose to be double clamped at each end with marine-grade stainless steel (if there is sufficient hose barb to allow it) as well as marked with the manufacturer’s name or trademark, year of manufacture and application on the outermost cover.

Access and inspect fuel tank fill hoses regularly for leaks and deterioration as part of your vessel’s maintenance program. Check that each end of the hose is double clamped and that the clamps are tight and free from corrosion. Replace older hose (regardless of appearance) as per the manufacturer’s recommendations.

Story and photos by Frank Lanier, Southern Boating September 2018