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Old 03 January 2017, 03:37   #11
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Country: UK - Scotland
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Boat name: charlie girl
Make: reiver 3.8/regal3760
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Your info re smoke at start up is exactly right. Have you checked the tacho with a shop tach as they can be inaccurate?
Iirc those engines are max rated at 3600? so maybe it's hitting the governor,you can do a high idle test to see if it is sitting on the governor. If it is it could be it's underpropped,either had the wrong prop fitted or been propped for very heavy loads.You would expect a little black smoke under hard acceleration so maybe the engine isn't seeing much load.
Correctly propped you should still be able to pull over 3600 at wot with a normal load & should run under max rpm (I think 3400 is max continuous rated speed?)
You need to be careful if you start switching props that you don't end up over propped which is worse than under propped
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Old 03 January 2017, 04:11   #12
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Boat name: Zodiac Hurricane 733
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Quote:
Originally Posted by beamishken View Post
Your info re smoke at start up is exactly right. Have you checked the tacho with a shop tach as they can be inaccurate?
Iirc those engines are max rated at 3600? so maybe it's hitting the governor,you can do a high idle test to see if it is sitting on the governor. If it is it could be it's underpropped,either had the wrong prop fitted or been propped for very heavy loads.You would expect a little black smoke under hard acceleration so maybe the engine isn't seeing much load.
Correctly propped you should still be able to pull over 3600 at wot with a normal load & should run under max rpm (I think 3400 is max continuous rated speed?)
You need to be careful if you start switching props that you don't end up over propped which is worse than under propped
What you are saying is pretty consistent with what i have learned. The boat came with a 16x13 towing prop was was turning 4500rpm at WOT under load. I changed the prop to a 15x19 prop and now it turns 4200rpm under load.

What i learned from browsing numerous marine diesel forums is that the
TAMD41-A is rated for 3800rpms @ WOT with a max Cruising rpm @ 3400 as you stated. So currently i am under-propped by 400rpms if my tach is functioning properly.

I am thinking that i want to keep it under-propped so when i load it down with 150 gallons of fuel, Gear, Dudes, Beer and a Moose i can still have plenty of power to push me over waves.

I actually think it might be easier on the motor if there isnt much load on it and you dont cruise above 3400rpms
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Old 03 January 2017, 04:15   #13
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Yeh exactly what I'd say only thing left to check is tacho which is an easy check
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Old 03 January 2017, 04:18   #14
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i appreciate the info guys, i have my first Bear & Deer hunting trip planned in April. I will also be installing a Crab pot puller on the rib for Crabbing & Shrimping on the same trip.
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Old 03 January 2017, 04:33   #15
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Yeh exactly what I'd say only thing left to check is tacho which is an easy check
Will do Bro, do you have the same engine? has it been reliable for you?
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Old 03 January 2017, 04:37   #16
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I think trim tabs are essential on slightly larger boats or boat with a proper deep v. Not only do they help with planning speeds but also correcting for lean into wind. However consider checking for extra weight that shouldn't be aft such as trapped water in the hull, also move anything mobile forward, store all ur junk forward, and try some mobile ballast forward temporarily. Maybe invest in a nice big anchor.

My first boat was a rather flighty regal and I used to carry two 20kg bags of sand forward, cost less than a tenner and on the odd occasions I needed the bow to lift up, I just cut and tipped them over the side.
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Old 03 January 2017, 04:54   #17
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Hi I don't have the same engine but have worked on a few
There a prety Hardy engine and are known for doing high hours no problem if cared for.
Some think they are better than the later engines with the electronic controls as there's less to go wrong
Their only down side is because their built more like a commercial engine there a bit heavy compared to others about but you can't have everything!

I think I'd definitely check the tacho as I'm a bit surprised the governor would let it rev to 4500rpm I'd expect it to stop the engine at 4200 -4300 ish on an engine rated to 3800 max I may be wrong but it just seems a long way over the rated speed
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Old 04 January 2017, 19:26   #18
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Prop it for maximum load so wait until you've got it sorted. However, the engine will not make more power at higher revs so getting it correct and not over revving is important.

I have trim tabs on my rib and wouldn't be without them. My advice is to ensure you have tabs which are long rather than wide. Wide is common so you may have to search them out - I made mine from fiberglass. The reason for length is that the upward lift the tabs provide is more effective the further aft they are and also when you run them flat you are effectively extending the hull length.
If you fit the tabs along the transom V as is common, another benefit you'll have is the ability to reduce the steering necessary when you are fighting a side wind. - When the boat lists on a side wind it will do so towards the wind since you will be steering into the wind to prevent the boat being blown off course, putting down a tab on that side will lift that side of the hull to counter the listing but it will also steer the boat into the wind, a little by drag but mostly because the tab is angled on the transom V and as you lower it you also provide some steering. Of course the result of this is that the tab levels the boat whilst also steering it into the wind. A double benefit.
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Old 05 January 2017, 05:53   #19
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Prop it for maximum load so wait until you've got it sorted. However, the engine will not make more power at higher revs so getting it correct and not over revving is important.

I have trim tabs on my rib and wouldn't be without them. My advice is to ensure you have tabs which are long rather than wide. Wide is common so you may have to search them out - I made mine from fiberglass. The reason for length is that the upward lift the tabs provide is more effective the further aft they are and also when you run them flat you are effectively extending the hull length.
If you fit the tabs along the transom V as is common, another benefit you'll have is the ability to reduce the steering necessary when you are fighting a side wind. - When the boat lists on a side wind it will do so towards the wind since you will be steering into the wind to prevent the boat being blown off course, putting down a tab on that side will lift that side of the hull to counter the listing but it will also steer the boat into the wind, a little by drag but mostly because the tab is angled on the transom V and as you lower it you also provide some steering. Of course the result of this is that the tab levels the boat whilst also steering it into the wind. A double benefit.
I am good on the propping, I am keeping it underpropped in anticipation of loading it down very heavy. This should not be an issue because I do not run this motor above 3200 rpms.

I like your view on trim tabs, but I have already ordered a set of retractable tabs. I think they will be fine on keeping the bow down which is my primary reason.

Eventually though, I think I am going to pull the diesel to free up deck space and weight & have a 3-4ft aluminum pod fabricated for the stern. Probably end up throwing twin E-Tec 225s on it. This is speaking years & years into the future though, just a dream.
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Old 05 January 2017, 12:03   #20
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Im not sure underpropped is a good idea. The boat is designed to carry a lot of weight. You'll probably never have enough weight to really load it down. I can't really tell the difference between 2 people and 13 people with a single 250 outboard. The boat is rated for twin 150s When I talked to hurricane during my rebuild they were happy I was staying with a single 250.

A diesel boat is not a race boat so who cares if you're a tad bit slower out of the hole. Prop it for how it runs 99% of the time, at cruise.

Rated payload on your boat is like 2500 lbs. and the boat probably weighs less than 5000lbs empty.

The bow is a big thing. Odd question, how tall are you? My teenagers couldn't drive it until they grew some.

Jason
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