River to Sea?

[mriley]

Would it be OK to take a boat that has been pootling up and down the river at 4kts for a few years to sea up to its design speed of around 30 kts. Engines petrol, 146hp with outdrives. Hull is designed for coastal. Any actions needed?, I have read a bit about cylinders glazing at low speed (but not how to deal with it)?? Thanks in advance.

 

[rustybarge]

Hi,

It's only diesels that suffer from low revs glazing, anything less than 3/4 load is going to cause trouble. A diesel is a high compression engine, at slow revs the piston rings don't press against the bores and polish the surface, causing blowback.

Most normal petrol engines run at half the compression ratio of a diesel. So the rings are designed to be happy in any part of the rev range.

Just check to make sure there's no gunge in the tanks which could be stirred up and block the filters.

...and get your fillings checked!

 

[pcatterall]

Would it be OK to take a boat that has been pootling up and down the river at 4kts for a few years to sea up to its design speed of around 30 kts. Engines petrol, 146hp with outdrives. Hull is designed for coastal. Any actions needed?, I have read a bit about cylinders glazing at low speed (but not how to deal with it)?? Thanks in advance.

I would be less worried about the engine and more concerned about all the other 'sea' stuff, safety equipment, communications, charts/navigation, crew competance etc. Prudence would certainly indicate some engine trials working up to full speed with out venturing far offshore.

 

[alant]

Would it be OK to take a boat that has been pootling up and down the river at 4kts for a few years to sea up to its design speed of around 30 kts. Engines petrol, 146hp with outdrives. Hull is designed for coastal. Any actions needed?, I have read a bit about cylinders glazing at low speed (but not how to deal with it)?? Thanks in advance.

What is it & where will you be "to sea"?

 

[alteredoutlook]

dont forget to consider anti fouling!

 

[jwilson]

Just check to make sure there's no gunge in the tanks which could be stirred up and block the filters.

+1 - one of the things you find doing yacht deliveries is how often the fuel filters get blocked - often the delivery crew will drive a boat harder in worse weather than any owner ever has, thus stirring up the muck in the tank. Taking a boat used for years in flat river water to any sort of chop/swell, even quite slight, will do the same.

Have at least two spare filters for each engine, know how to fit them and be prepared to do so, unless you clean the tank or tanks first. And don't be surprised how much fuel nearly 300 hp uses at speed.

 

[gary111160]

dont forget to consider anti fouling!

.....and anodes if staying in salt water....

Gary