5 Tips for Repowering your Boat

Lack of engine access on some boats can add significant cost to a repower project.

I have estimated and overseen dozens of repower jobs—mostly on inboard powerboats over 30 feet, but also on I/O’s, sailboats, and outboard boats. Replacing any boat’s engine(s) is a project that should make financial sense. So whether you have an older boat you wish to keep, you have a just purchased a “fixer” in hopes of bringing it back to life, or you want to repower your old boat because it is tough to sell without a new engine, I have a few words of advice.

1. The current used boat market is awash with more boats than buyers. An old boat with mechanical problems may be next to impossible to sell unless you are willing to practically give it away—or repower. The engines in most powerboats typically represent more than fifty percent of the value of the boat. So know the price range for the boat, in excellent condition, before proceeding with a repower.

2. When estimating any repower, bulk up the budget beyond the cost of the engine and installation. On inboard engines you must consider replacing old engine mounts, wiring, controls, exhaust systems, fuel tanks, transmissions, stuffing boxes, cutlass bearings, struts, shafts, and props while you have the engine out.  If the engine is old and tired, chances are these items are, too.  Shafts and props are something you’ll want to match to the new engine’s horsepower. You’ll also want to think about dolling up the engine space up with new paint, lights, and sound-proofing to make the transformation complete. For I/O boats, add budget for making sure the bellows are watertight and the lower-end serviced. On outboard boats, add budget for outboard brackets, transom repairs/adjustments, and controls. You may not have to replace any of these things, but you should know what it costs in advance of a repower and have a contingency budget just in case.


This boat is listed for sale on boattrader.com and probably needs a repower–calculate if she’s worth it.

3. A boat’s engine access can also add significant costs.  Many boats are built with the engines installed before the deck is fastened in place. While there is a hatch to inspect and access the engine room on virtually every boat, you can’t always remove the engine without cutting out a bulkhead or deck. On a wooden boat this will add a whole new carpentry cost. On fiberglass, there are many additional costs in order to make the repair look like it never happened. When the house or superstructure of the boat don’t allow crane access to the engine(s), staging a rail system to hoist the engine out might be required. And of course there’s a charge for that too!

4. Budget concerns might lead you to consider buying a used or rebuilt engine rather than a new one. New or factory rebuilt engines with warranties provide peace-of-mind for you, and will be more attractive to any buyer.

5. You can install your own engines; however, you will need to pay to get them inspected by an authorized dealer who can activate the warranty. Alternatively your authorized installer will submit the warranty paperwork on your behalf. Used engines without warranties cost as much or more in labor to install, and they have little proof of engine hours, condition, or warranty for a would-be-buyer.

When I used the advanced keyword search on boattrader.com I came up with 760 boats that had the word “repower” in the description.  A new engine should make your boat more fuel efficient and possibly faster, and it will certainly make it more attractive to future buyers. So while a repower job is challenging to do and a financial risk, it might just be worth it.



  1. TH Marine says:

    Some great insights in your article. Another item to consider is a jack plate that allows you to move your outboard motor up and down. This allows you to maximize fuel consumption while adding speed. visit http://www.thmarine.com to browse our selection of jack plates and atlas jack plates.

  2. My sister and her husband have had a boat for almost four years now without any real problems. After a long winter, they tried to get it up and running on the lake and the engine wouldn’t even start! Her husband has tinkered with it a bit to see if he could figure out what was going on. Hopefully they can get the repairs that they need without having to cut a hole in their deck like you talked about. Thanks for sharing!