Why Buy From Us?

We are a real brick and mortar boat business not just a virtual online presence. We are located in Aberdeen, Washington as Crowley Marine Certified Service and Sales. We have over 40 years experience as a factory certified repair shop.

When you buy from Rainboat.com, you not only get quality new and re-manufactured name brand products, you also get one year of free access to a corresponding electronic SELOC manual (for major components) along with free DIY tech support from a certified technician. 

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Tech Tips and Guides

Oil Mixture for Break-In of 2-Stroke Engines


The first 10 hours of use are when you are breaking in your new or rebuilt engine.  It's important to follow these guidelines so that your engine and all it's parts are sufficiently lubricated and will continue to run smoothly in the long run.

Two-Stroke Oil Injection Outboards

During break-in, all new Precision Blend engines should be run on double oil, with the exception of HPDI motors, which use straight gas for break-in.  This means you need to run all PBS-equipped engines on a 50:1 oil mix during the 10-hour break-in period to supplement the oil supplied by the oil injection system.  This additional oil provides further protection during the oil pump setup and furnishes extra lubricating oil during the break-in period. 

Two-Stroke Premix Outboards

Pre-mix engines that normally run on a 50:1 ratio will need a break-in oil ratio of 25:1 during the first 10 hours of operation.  Engines that normally run at 100:1 should be run at 50:1 during break-in.  After the 10-hour break-in period, use the regular oil ratio. 

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A propeller converts the engine’s power to thrust that drives the boat.  As the propeller turns, low pressure is created on one side and high pressure is created on the other side.  The propeller moves toward the low pressure, moving the boat with it.  How well a propeller moves toward the low pressure depends on several factors. 

  • Thin blade (low resistance)
  • Diameter (thrust)
  • Pitch (load)

No one single propeller design will work for all applications.  Hull weight and available horsepower dictate what will work for best for you.  You need to keep in mind the operating range of the engine and select a propeller that will allow the engine to come close to its maximum RPMs at WOT (wide-open throttle). 

Two important terms to become familiar with are ventilation and cavitation.  Both are issues that can occur from poor rigging, improper prop selection, or a damaged propeller.

Ventilation is a problem that means air is being pulled into the propeller from the surface of the water or from exhaust gasses while in reverse.  The ventilation plate on the lower unit tries to limit this problem.  Prop design or high mounting height can be possible sources for this issue.   It is not unusual to vent the prop with some hull designs during hard turns. 

Cavitation describes water that is actually boiling on a surface because pressure has dropped so low.  A damaged prop blade will cause a very low-pressure area behind the damaged area.  Water boils at 212 degrees at sea level.  Dropping the pressure on a prop blade enough will cause the water to boil until it moves across the blade to a high-pressure area. 


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Tech Tip: Converting Your Outboard Lower Unit to a Jet Drive

So you want to take your boat upriver. That can be tough on the on traditional outboard lower unit. Many boaters prefer to convert their standard propeller driven outboard to outboard jet drive. Jet boats are able to travel across shallow sections of river without damage to the drive.

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