heavy displacement repower dilemma

[zeehag]

think about this a minuet---most heavy displacement boats love their weight and handle strangely when some racing sailor decided arbitrarily to cut the weight on board. waken to the fact that heavy displacement is just that and LOVES weight. there is a reason for every pound on these. same as to location of that on board weight. not so for the light racer sailors. but heavy displacement talking reduction of weight is a lil strange. doesnot even fit right into the sentence.
consult a marine architect before arbitrarily deciding to remove the important weight that makes boat handle properly. of course i amnot dvocating a 2 inch freeboard.. just be aware of what makes your boat handle best. i found that adding weight is what my boat craves--- so we are doing just that. midship low to keel and a hard dodger, among other goodies
have fun.

[nhschneider]

I used to make my living as a mechanic in the heavy equipment industry (primarily agricultural and earth-moving equipment although I did more than my share of work on over-the-road truck-tractors - I also served time as a service manager for a truck and tractor dealership) and I have yet to find an engineer who will sign his or her name to the statement, “Diesels like to be run at 80% of their rated capacity.” They would likely be much more willing to sign their name to a statement like, “Modern Diesel engines will reliably deliver power over a wide range of operating speeds and conditions.”

If you’ve talked with any trawler owners, you’ll probably find that a majority of them run their engine(s) at barely above a low idle yet those engines will deliver thousands of trouble-free hours. However, the worst offender of low-load operation is probably a crane which will often idle for 90% (or more) of the time. They don’t make special engines for cranes nor do they suffer from premature failure.

Furthermore, I feel that turbochargers are a poor application for cruising sail boats. Very few cruisers operate their engines at enough load to generate exhaust gas velocity where a turbo will ‘spool up’. This can and does cause a carbon buildup that can and does foul the turbo’s impeller, not only rendering it useless but impairing the operation of the engine. In Yanmar’s owner’s manual for their turbo-equipped yacht engines, it states that prior to shutdown, the engine(s) should be revved to Wide Open Throttle and back to low idle five times (in neutral, of course). Their intention is to clean out any carbon that might have formed on the turbo.

My Beta Marine 90 is hardly ever run more than 1,400 RPM and has over 4,000 hours on it. It still uses no oil between changes.

Fair winds and calm seas.

[Salmoneyes]

Originally Posted by zeehag

think about this a minuet---most heavy displacement boats love their weight and handle strangely when some racing sailor decided arbitrarily to cut the weight on board. waken to the fact that heavy displacement is just that and LOVES weight. there is a reason for every pound on these. same as to location of that on board weight. not so for the light racer sailors. but heavy displacement talking reduction of weight is a lil strange. doesnot even fit right into the sentence.
consult a marine architect before arbitrarily deciding to remove the important weight that makes boat handle properly. of course i amnot dvocating a 2 inch freeboard.. just be aware of what makes your boat handle best. i found that adding weight is what my boat craves--- so we are doing just that. midship low to keel and a hard dodger, among other goodies
have fun.

Interesting point and I do agree.

We do have professional input, plus I am an avid reader and Gerr books make up a lot of our library. Our D/LWL ratio is 447. The designer has it at 287. Id be happier at 300.
That said, the professional option has been synthesized to this.
The hull was overbuilt from the plans, (33% heavier) so will not sail as designed.

We can leave it alone and make do with what it is, or modify. Since the hull has corrosion, I am blasting every inch inside and out for repairs and paint. That means I can easily make changes to lighten her. This could be as simple as removing heavy steel water and fuel tanks and swapping for lighter materials, and relocating to the hollows of the keel. The hull below water line is 33% heavier than designed but they put more lead ballast in then the plans call for, so finding the correct balance may be enough. We can remove the second bathroom which reduces the amount of bulk heads. Different interior (there was nearly 4000 lbs of teak in this girl. Just so many ways to skin this cat really.

It really needs a whole new stability book created (we will do this asap) to determine many things, one of which is HP required, weight allowed for engine, and correct placement. Since there are so many options, I decided to try to make the engine decision first, with known weights and work around that. I KNOW THAT IS ASS BACKWARDS, but in our case we need to make some concrete decisions, and to do that, I need to choose between new, light weight efficient, or old school simplicity. I am leaning toward the latter.

The main reason for this original question, was to see what folks who live permanently on their boats, and cruise extensively have, why, and the pros and cons. From a few of the responses, it sounds like simplicity is "wiser" than efficiency. This was my gut feeling all along, but it had the potential to drop 5 to 700 pounds. I can keep old school simplicity, and make weight reductions elsewhere.

I wanted to be sure I clarify that I listen and respect the professional help and input, but at the same time, I always listen to experience, where ever it comes from, and balance the information. When they all agree, it makes my decisions much easier.

Additionally, I am not reluctant to make corrections that require a lot of time and energy, but if the cost to fix and repair financially out weighs replace, then I replace. We are not there yet, but the thought of building a new hull from aluminum, is starting to look very good...

[Salmoneyes]

Originally Posted by nhschneider

I used to make my living as a mechanic in the heavy equipment industry (primarily agricultural and earth-moving equipment although I did more than my share of work on over-the-road truck-tractors - I also served time as a service manager for a truck and tractor dealership) and I have yet to find an engineer who will sign his or her name to the statement, “Diesels like to be run at 80% of their rated capacity.” They would likely be much more willing to sign their name to a statement like, “Modern Diesel engines will reliably deliver power over a wide range of operating speeds and conditions.”

If you’ve talked with any trawler owners, you’ll probably find that a majority of them run their engine(s) at barely above a low idle yet those engines will deliver thousands of trouble-free hours. However, the worst offender of low-load operation is probably a crane which will often idle for 90% (or more) of the time. They don’t make special engines for cranes nor do they suffer from premature failure.

Furthermore, I feel that turbochargers are a poor application for cruising sail boats. Very few cruisers operate their engines at enough load to generate exhaust gas velocity where a turbo will ‘spool up’. This can and does cause a carbon buildup that can and does foul the turbo’s impeller, not only rendering it useless but impairing the operation of the engine. In Yanmar’s owner’s manual for their turbo-equipped yacht engines, it states that prior to shutdown, the engine(s) should be revved to Wide Open Throttle and back to low idle five times (in neutral, of course). Their intention is to clean out any carbon that might have formed on the turbo.

My Beta Marine 90 is hardly ever run more than 1,400 RPM and has over 4,000 hours on it. It still uses no oil between changes.

Fair winds and calm seas.

I love A Ha moments... This would explain why I see guys reving the engines before shut down... Some one else mentioned it here and no good explanation was given.

I hauled frac sand in ND for a couple years (winters) and never shut off my truck except for oil changes. It was common with every one. But when I ran it, I ran it hard. In the early 80s I hauled cotton and it was the same thing. I would of thought that if it were a matter of longevity (not pollution) then that practice would of stopped years ago.

Since your background is in diesels, maybe you can help guide with this idea.

As I understand the workings of diesels, more fuel makes more power. (in very simple terms). SO if I were to replace my injectors and recalibrate my pump, and even have a cam ground accordingly, I could lower the HP out put of my 130hp so it matches my hull requirements and runs as efficiently as possible at a given RPM range. ??

[Salmoneyes]

Originally Posted by LotNick

What about one of those Chinese clones? Simple, naturally aspirated, HF-4102 at 70HP should be less than 4k USD with gearbox included. I would definately investigate...

Just looked... I really do not know how all that stuff on Alibaba works. I saw some 14 foot aluminum boats on there a few weeks back. After looking much closer, they were exactly the same as a Lund model that is very popular around here. I started thinking that maybe a lot of the stuff we buy here is coming from China, and rebranded.
Maybe that is why all the hub bub about tariffs and such. The boat in question was 1400 and when you buy from Lund its 8500.. I get tax, and import and all that, but why can't we crank out boats for 1400?

[Cadence]

Originally Posted by nhschneider

I used to make my living as a mechanic in the heavy equipment industry (primarily agricultural and earth-moving equipment although I did more than my share of work on over-the-road truck-tractors - I also served time as a service manager for a truck and tractor dealership) and I have yet to find an engineer who will sign his or her name to the statement, “Diesels like to be run at 80% of their rated capacity.” They would likely be much more willing to sign their name to a statement like, “Modern Diesel engines will reliably deliver power over a wide range of operating speeds and conditions.”

If you’ve talked with any trawler owners, you’ll probably find that a majority of them run their engine(s) at barely above a low idle yet those engines will deliver thousands of trouble-free hours. However, the worst offender of low-load operation is probably a crane which will often idle for 90% (or more) of the time. They don’t make special engines for cranes nor do they suffer from premature failure.

Furthermore, I feel that turbochargers are a poor application for cruising sail boats. Very few cruisers operate their engines at enough load to generate exhaust gas velocity where a turbo will ‘spool up’. This can and does cause a carbon buildup that can and does foul the turbo’s impeller, not only rendering it useless but impairing the operation of the engine. In Yanmar’s owner’s manual for their turbo-equipped yacht engines, it states that prior to shutdown, the engine(s) should be revved to Wide Open Throttle and back to low idle five times (in neutral, of course). Their intention is to clean out any carbon that might have formed on the turbo.

My Beta Marine 90 is hardly ever run more than 1,400 RPM and has over 4,000 hours on it. It still uses no oil between changes.

Fair winds and calm seas.

Very nicely stated.

[dkenny64]

Originally Posted by captlloyd

I am very big on the non computerized Cummins. I had a 5.9 that many people swear by for marine use, dry stacked and keel cooled. Just loved it, these things go for 250-300 thousand miles in trucks. I really did nothing to it as far as marinizing it. They have 3&4 cylinder versions also and I gave $1500 for my 5.9. They are available new or used everywhere.

I think you're under estimating mileage in trucks.. I've got 332K miles on my truck and it runs fine..I know of may others that are over 500k miles..many make to 1million miles.. mines a computer 24v... the older 12v lived even longer..


-dkenny64

[nhschneider]

Originally Posted by Salmoneyes

Since your background is in diesels, maybe you can help guide with this idea.



As I understand the workings of diesels, more fuel makes more power. (in very simple terms). SO if I were to replace my injectors and recalibrate my pump, and even have a cam ground accordingly, I could lower the HP out put of my 130hp so it matches my hull requirements and runs as efficiently as possible at a given RPM range. ??

You’re asking an engineering question and I have no experience in engineering. I’m pretty conservative when it comes to making alterations to any engine. However, it might work but I think that’s what more likely is that you would have significant problems.

I suggest that you install an engine that’s suitable for your installation.

Fair winds and calm seas.

[nhschneider]

Originally Posted by Cadence

Very nicely stated.

Thank you.

[nwdiver]

If you are looking at keel cooled and dry stack, look at Lugger.......John Deere in it marine form.....which of course Deere does itself now......thr NW coast fishing fleet (or much of it) can't be all wrong......

[Salmoneyes]

Originally Posted by nwdiver

If you are looking at keel cooled and dry stack, look at Lugger.......John Deere in it marine form.....which of course Deere does itself now......thr NW coast fishing fleet (or much of it) can't be all wrong......

Yep, very popular here in Oregon... Keel cool is to allow the engine to run at proper temps (190 to 200) but we will run wet exhaust.

[captlloyd]

Originally Posted by dkenny64

I think you're under estimating mileage in trucks.. I've got 332K miles on my truck and it runs fine..I know of may others that are over 500k miles..many make to 1million miles.. mines a computer 24v... the older 12v lived even longer..


-dkenny64

You are right. I didn’t use the real numbers because a lot of people just don’t believe it. But even 250-300 thousand is impressive.

[Salmoneyes]

Originally Posted by captlloyd

You are right. I didn’t use the real numbers because a lot of people just don’t believe it. But even 250-300 thousand is impressive.

Off topic but yep, these are crazy reliable. I personally saw a 600k plus 12v that was starting to burn oil so they pulled it, but it still ran strong.

For our purpose, this motors too much power and is no smaller or lighter than what we have. Parts availability would be the only advantage for choosing a 6B cummins.

The 4B would be great, but 2 issues of concern are
1. 800Lb motor (saves 200lbs) is not a major reduction for the expense of a swap
2. Ive heard from others that they feel the vibration from the 4B is higher than desired.

I looked into it, and I can find no reasonable explanation for that.

[PeterS]

[QUOTE=
2. Ive heard from others that they feel the vibration from the 4B is higher than desired.

I looked into it, and I can find no reasonable explanation for that.[/QUOTE]

The 4 cylinder B does vibrate more, 4 cyl engine 2 pulses per revolution, 180 degree cycle, 6 cyl 3 pulses per revolution, 120 degree cycle.

A V8 is very slightly less smooth than a 6 cyl, basically from there the more cylinders the smoother the engine. The straight 6 also delivers the most torque for its size.

The 5.9 6BTA is made without turbos for commercial use, not sure these days what HP they are but the weight is significantly lower without the turbo, inter-cooler and around 3 gallons less coolant. The turbo version with reduction gear, lubricant & fresh water weighed 1047 Lbs.

Those mechanical diesels were also the first diesel to pass the US Navy 1000 hour test, circa 2000-2002, I am unsure how many engines have passed that test to date.

[PeterS]

sorry that should read 2 gallons less coolant