Approx weight of a 1990 41' convertible?

[markawilson]

Am evaluating the props on boat as we feel like we are overpropped and are not getting 2800 rpms. Would anyone know the approx weight of the 1990 41 convertible with 3208ta's? A fiberglass hardtop was added. We run the boat heavy, always full fuel and water, plenty of ice in bow chests, full cockpit and bait tank, plus tons of gear, etc., etc. Is it better to estimate a little on the high side weight wise?

Thanks!

 

[Vincentc]

According to the 1995 McKnew Guide the weight is 35,400#. I suppose that number is comparable to the average weight of say a 5'10 male. There are a lot of variables.

 

[garyd]

41' is sensitive to weight. We run twin 625hp. and it is still sensitive to weight.

The first thing you should do is remove all non essential items "ALL OF THEM".

Next empty the holding tank, empty the water tank, make sure the bottom and props are clean.

about 1/4 fuel, no extra anchor or props, refrigerator light as possible. I mean make her light, CLEAN OUT THE GALLEY.

Then see what you get out of her both speed and performance including RPM and fuel burn ETC .

Use that as your base line. From here on out that is your light base line.

3208's are going to strain to move this bad boy. Any extra weight will slow you down. Every pound you bring on is either going to slow you down or increase fuel burn.

We run 26 x 29 cupped props. 1986 41 convertible t-625 DDEC. cruise 24-26 kts WOT 33kts.

Now when you add the stuff back on board you can see the performance change.

Water full= 1,200 lbs
fuel add 3/4 to full = 2,250 lbs
holding tank 1/4 = 100lbs
Tools, spare anchor etc = 250 lbs
Galley stuff = 200 lbs
Refrigerator full = 100 lbs
Misc= 350 lbs


TOTAL ADDITIONAL WEIGHT FROM BASE = 4,450 lbs over 10% of total weight.

Max loaded base line. Again check your speed and performance.

Now your ready to determine what props you want. As u said if your going to run her heavy all the time you may need to reduce the pitch by at least 2. Maybe more if necessary.

Good luck let us know how it turns out.

garyd

 

[markawilson]

Thank you Garyd for the comments!

I have owned the boat for 2.5 yrs and I do not know if she turned up 2800 when we bought and sea-trialed and surveyed her. It is only in these two years I have learned the importance of WOT rpms and wheel adjustment to achieve the optimal loading on the engines.

Generally speaking we feel like this boat 'light' will run about 19k WOT and cruise at 16k at about 2200 rpms. Since we are ALWAYS heavy, we get about 14k at cruise or 8-9k at 12-1400 rpms for night travel. Usually we are happy to see 14k at 2150 rpms loaded down with people and gear - we think this is the optimum fuel burn/cruise speed.

In addition to all you mentioned, we always carry scuba tanks and multiple sets of dive gear, hundreds of lbs of fishing tackle/6 sets of tiagra 50w's, and lots of clothes/towels etc in the drawers and cabinets. Usually we have 5-6 people minimum. So I am thinking we have 10k lbs minimum of weight over the base boat plus outriggers, fiberglass hardtop over bridge, etc.

I am having the port gear replaced right now and intend to address the wheels and WOT in this batch of work. We will unload her as you suggest and then go see what we get and plan accordingly.

But for the computer programs that calculate what you should use pitch wise(such as on boatdiesel.com) I will use 40,000 lb as a starting point, sound about right?

Thanks again!

 

[garyd]

If you put 10k worth of stuff on it then I believe that would be about 1/2 fuel.water.holding tank. Next time you pull it ask them how much it weighs. Most travel lifts have a scale.

garyd