Trawler VS Express (Space vs Speed)?

[Birdman]

In this case, his Sea Ray has exactly the same engines I've got (same year Mercruiser 454 / 340hp). There's definitely no vacuum pump or anything that could possibly cause a siphon. Crankcase is just vented to the flame arrestor, not to manifold vacuum or anything. The only way you're getting water from the exhaust into one of those engines is if you either fill the exhaust and overflow the riser backwards into the engine, or if the riser is too low in the system, water is left over in there and it splashes back into the engine after shutdown.

My buddies 39 ingested water both ways: during running, after 1.5 hours, slowed down to a 54mph zone, 10 minutes into 5mph seize! Full of water. Another time, we ran 2 hours, then went thru a 5mph zone for 30 minutes, then ran at cruise for 20 minutes and seize! From 20+ or so knots to 0! Full of water again. That's just 2 of 4 occurrences he had, of which I was with him (not on his boat, but he was following me). The other 2 I was not present for...

 

[Birdman]

I believe I already did that on this post and explained why - we are also on Long Island as well and tidal currents cannot be ignored where we cruised with a trawler.

Yes you did, thanks!! Looking for more on both sides!

 

[Art]

Quote:
Originally Posted by Art View Post
Clamp-on Exhaust Tip Flappers - EZ PZ!! No water into exhaust back pressure from wakes or otherwise.

https://www.summitracing.com/parts/e...SABEgIPwPD_BwE
______________________________________________________________

: Those were tried, an anti-siphon contraption (designed specifically for the 39 junkray) in the risers was tried, and lifting the motors (put on a better angle) was tried, all to no worky.

:

Birdman

Noticed I mentioned - Clamp-on Exhaust Tip Flappers - No water into exhaust back pressure from wakes or otherwise.

That is true [regarding "wakes or otherwise" hitting transom] i.e. that Flappers do work for stopping water to be pushed reverse direction into exhaust pipe in those conditions/instances.

Now - If in the boat engine to exhaust configurations you mention somehow sucks its own reverse-direction flow of water into the exhaust and then up and into the engine - then yes - Flappers would likely not cure the problem. Seems the items you mentioned of engines filled with water and ceasing up means the marine design architect made big error.

 

[rslifkin]

My buddies 39 ingested water both ways: during running, after 1.5 hours, slowed down to a 54mph zone, 10 minutes into 5mph seize! Full of water. Another time, we ran 2 hours, then went thru a 5mph zone for 30 minutes, then ran at cruise for 20 minutes and seize! From 20+ or so knots to 0! Full of water again. That's just 2 of 4 occurrences he had, of which I was with him (not on his boat, but he was following me). The other 2 I was not present for...

That's either bad exhaust system geometry or failed risers or gaskets. Those risers only last a few years typically.

 

[Ritser]

Have you evaluated a Krogen Express?? We are live aboards during 5-6 months and use our Krogen Express 49 as a displacement trawler. We log roughly 450-500 engine hours. Occasionally we push the handles to WOT when depth, room in abscense of other boats.

 

[Birdman]

Quote:
Originally Posted by Art View Post
Clamp-on Exhaust Tip Flappers - EZ PZ!! No water into exhaust back pressure from wakes or otherwise.

https://www.summitracing.com/parts/e...SABEgIPwPD_BwE
______________________________________________________________

: Those were tried, an anti-siphon contraption (designed specifically for the 39 junkray) in the risers was tried, and lifting the motors (put on a better angle) was tried, all to no worky.

:

Birdman

Noticed I mentioned - Clamp-on Exhaust Tip Flappers - No water into exhaust back pressure from wakes or otherwise.

That is true [regarding "wakes or otherwise" hitting transom] i.e. that Flappers do work for stopping water to be pushed reverse direction into exhaust pipe in those conditions/instances.

Now - If in the boat engine to exhaust configurations you mention somehow sucks its own reverse-direction flow of water into the exhaust and then up and into the engine - then yes - Flappers would likely not cure the problem. Seems the items you mentioned of engines filled with water and ceasing up means the marine design architect made big error.

They tried flaps, anti siphon mechanism in exhaust, specially designed risers.... all to no avail. It is simply put, an disgrace of a design by junkray, period. This is just one example of searay issues I've personally seen with my own eyes. It is absolutely amazing to me they get away with this crap, and still sell boats. I'd just assume sinking them all, it would make a great artificial fishing reef!

That's either bad exhaust system geometry or failed risers or gaskets. Those risers only last a few years typically.

Among other things with "bad geometry". The motors aren't even mounted properly on the 39 model. The merc cruiser engineers shake their head when they see it. Personally witnessed that myself also on my buddies boat.

Have you evaluated a Krogen Express?? We are live aboards during 5-6 months and use our Krogen Express 49 as a displacement trawler. We log roughly 450-500 engine hours. Occasionally we push the handles to WOT when depth, room in abscense of other boats.

I absolutely LOVE both the Krogen's and the K Express designs. But are you going to find me a used one for 2-300k?

 

[Art]

Birdman

Can you clearly describe the mechanical/design reasons or provide a diagram as to what actually made the water flow back into Sea Ray engines? I'm interested...

Thanks,

Art

 

[Birdman]

Birdman

Can you clearly describe the mechanical/design reasons or provide a diagram as to what actually made the water flow back into Sea Ray engines? I'm interested...

Thanks,

Art

No, sorry. I'm not any kind of mechanical expert or mechanic for that matter. I'm only going on what I witnessed personally 3 times, and what was told the other couple of times it occurred. And then what the engineers and mechanics evaluating it were saying. And then lastly, the 100's if not 1000's of posts, articles, complaints, lawsuits... on the same subject.

 

[rslifkin]

I dug around and found some more pictures. What I'm thinking is that there's just not enough drop from the risers to the lift mufflers, and there's a lot of pipe in between as well. So I'm betting under the right conditions it's possible to get the mufflers and such full enough that you could slosh a slug of water forward, over the riser and into the engine. I'm a little surprised it would happen with it running though, especially anything above idle.



Personally, my suggested fix would be to raise the risers as high as overhead clearance allows, then either relocate the mufflers closer to the engines to put more of the system after the post-muffler spillover and/or to add an overboard drain in the lower part of the muffler. Not enough to divert all of the water, but enough to limit how full the muffler gets and to mostly drain the system after shutdown.

 

[Birdman]

Personally, my suggested fix would be

My suggested "fix" is do not buy a searay!

 

[markpierce]

A 40 footer of any kind that can run safely in 3 feet of water is going to be very hard to find. My 38 draws 3'8" to the props, so figure you don't ever want to be in less than 5 feet of water. Something with prop pockets will draw less, but 3 feet of water is still tight. As an example, my dock neighbor's Sea Ray 390 EC draws less than 3 feet (around 2'6" IIRC), but 3 feet of water would still be a serious risk of a prop strike.

Same depth for my 35-footer. Thankfully, the rudder and propeller are keel-protected.

 

[rslifkin]

Same depth for my 35-footer. Thankfully, the rudder and propeller are keel-protected.

My rudders don't hang lower than my keel (or props), but my props are the lowest point by 5 inches. It's rarely a point of concern for me though.

 

[markpierce]

My rudders don't hang lower than my keel (or props), but my props are the lowest point by 5 inches. It's rarely a point of concern for me though.

Twin propellers/rudders are typically more subject to damage compared to a single.

 

[rslifkin]

Twin propellers/rudders are typically more subject to damage compared to a single.

Yes, I'd take more damage in a hit. But a planing single typically won't have a deep keel and skeg anyway. And the single bigger prop mounted lower would mean more draft. So unless you're in log infested or extremely shallow waters regularly, it's not a huge advantage either way.