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Author Topic:   130 Sport: Bow Ballast
mccomas posted 04-29-2005 10:19 AM ET (US)   Profile for mccomas   Send Email to mccomas  
Has anyone ever considered using ballast in the [bow] of their 130 SPORT? With two people sitting in the back seat, my boat is so tail heavy that in rough water there is a significant delay to plane preceeded by a realy high nose pitch-up. It also has a tendency to pitch up in rough water which is significantly reduced if I beat the heck out of my passenger by having him sit in the front of the boat.

I suspect that ballast would take off a bit from the top speed. Any thoughts?

Buckda posted 04-29-2005 11:55 AM ET (US)     Profile for Buckda  Send Email to Buckda     
Consider using some small water bladders up there like the wakeboard crowd uses to help their ski boats (made to NOT throw a wake) throw a big wake so they can "get air".

These bladders could be emptied when not in use, and re-filled when conditions warrant.

Just a thought, and I don't have any information about the sizes/weights that these bladders come in. I suspect that they might be too large for your application...but something similar might work...but to get to 180 pounds of "replacement" person up there in water, it takes about 30 gallons of water.


Mako posted 04-29-2005 12:14 PM ET (US)     Profile for Mako  Send Email to Mako     
What I do is make the passenger get up and move to the front seat (they can even face backwards) until I'm on plane, then they return to the rear bench. Otherwise, a hydrofoil (Stingray Jr for me) helps a bit. Having the 40hp two-stroke would probably help even more!
Phil Tyson posted 04-29-2005 07:16 PM ET (US)     Profile for Phil Tyson  Send Email to Phil Tyson     
One idea for the water ballast.

When I used to go to the Adirondacks to camp (Racquet Lake) my buddy had clear plastic bladders to carry potable water. These were I think 10 gallons, rectangular in size with a handle and a spout/fill.

Check some camping sites for comparables.

Phil Tyson posted 04-29-2005 07:22 PM ET (US)     Profile for Phil Tyson  Send Email to Phil Tyson     
Well, I did a quick search. Go to www.ems.com and search on RELIANCE 5-Gallon Fold-a-Carrier

This is the style I was referring to.

Hope this helps.

where2 posted 04-29-2005 11:42 PM ET (US)     Profile for where2  Send Email to where2     
As a test run, you could put a large heavy duty trash bag inside a duffle bag, and fill it with water.

I have a 15' Sport and have considered trying out the trash bag in the duffle bag to see if it would push the pointed part of the bow through the waves with two passengers on the rear thwart seat... I tried filling the bow anchor locker with water once, but it sloshes out too easy...

jimh posted 04-30-2005 10:54 AM ET (US)     Profile for jimh  Send Email to jimh     
[Administrative post]
jimh posted 04-30-2005 10:56 AM ET (US)     Profile for jimh  Send Email to jimh     
[Moved to this area.]
bigjohn1 posted 05-02-2005 09:23 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
mccomas, if any boat was a candidate for a Doelfin, yours is. I think with your setup, you will see a healthy improvement - a bit moreso than larger boats using this same fin. Although I have not owned a 130, I have owned three Zodiacs for diving over the years. They all had the same problem you have. I just got a gear placement routine down whereby all my gear went way up forward, this along with the Doelfin, cured the nose-up thing.
mccomas posted 05-02-2005 10:18 AM ET (US)     Profile for mccomas  Send Email to mccomas     
I am intreagued by the idea of the doel fin. How and where do I go about getting one? Is this something that comes in various sizes? Can my dealer order and install one?

Thank you all for your excellent comments!

mccomas posted 05-02-2005 10:24 AM ET (US)     Profile for mccomas  Send Email to mccomas     
sorry... doelfin
Mako posted 05-02-2005 01:37 PM ET (US)     Profile for Mako  Send Email to Mako     
You can pick up a Doel-Fin from West Marine, Boater's World, Overton's, etc. If you can bring yourself to drill 4 holes in your motor, you can install it yourself.

It makes the outboard trim much more effective, allowing you to keep the bow down to get on plane or cut thru small rolling swells. Lots of people on this forum use them and like them, myself included.

bigjohn1 posted 05-03-2005 08:29 AM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
If memory serves me, the Doelfin comes in standard size and a "junior" size for smaller outboards. I used the standard size on two Merc 40 2-strokes and a Merc classic 25. The standard size does look rather large on the smaller outboards but I wanted all the help I could get.
Royboy posted 05-03-2005 12:11 PM ET (US)     Profile for Royboy  Send Email to Royboy     
mcomas, is your engine the 25 hp 4-stroke Big Foot? Mine is, and it's very sensitive to both load distribution and also wind direction when trying to get on plane. I've been considering a four blade prop to solve this, but haven't learned enough about it yet to take the plunge.

Roy
Ichthus
130 Sport

jimmy c posted 05-04-2005 10:53 AM ET (US)     Profile for jimmy c  Send Email to jimmy c     
Doel Fin Doel Fin Doel Fin

I have great luck using them on 13 super sport, 13 gls,
I asure you will be pleased with the results,I would not be without one on any small boat.

P.S. there are other makes of this product that work equally as well.

billyc posted 05-04-2005 08:59 PM ET (US)     Profile for billyc  Send Email to billyc     
I have a 2000 13 foot Whaler (13 Sport) that I understand has the same hull as the current 130. It is powered by a 25 HP Bigfoot 4 stroke with 11" pitch ss prop.

I use a standard size Doelfin. The boat performs well with 2 people and lots of gear.

I installed a trolling motor last year and initially stored the battery (70 lbs ?) just behind the bow deck. The boat was on plane quicker and seemed to have a better ride. Then along came a large skier's wake and I took water over the bow. After the third or forth time this happen I relocated the battery under bench seat.

My advice: Install the Doelfin...forget addtional bow weight.

Royboy posted 05-04-2005 10:51 PM ET (US)     Profile for Royboy  Send Email to Royboy     
Just realized from the last post that I've been mis-identifying my Whaler!! I have the 2000 13 footer and just assumed it was a "130" although the I.D. plate says 13 Sport. I stand corrected.

Roy
Ichthus
13 Sport

mccomas posted 05-14-2005 02:39 PM ET (US)     Profile for mccomas  Send Email to mccomas     
Ok, I purchased a hydro-foil. I posted the results of the sea-trial in the performance section:

http://continuouswave.com/ubb/Forum4/HTML/003513.html

Royboy posted 05-17-2005 09:15 AM ET (US)     Profile for Royboy  Send Email to Royboy     
That's http://continuouswave.com/ubb/Forum4/HTML/003513.html
Royboy posted 05-17-2005 09:24 AM ET (US)     Profile for Royboy  Send Email to Royboy     
So is this just the "cheap" solution? Is there a different prop that would help these 4 strokes get on plane faster? I'm a bit leery of screwing stuff to my engine, and I frankly don't much care for the band-aid look these things give a boat. I'd install one of it were really the best alternative, but so far I haven't heard anyone chime in with propeller solutions. Surely these add-ons aren't the catch-all solution to poor engine performance. Or are they?

Roy

Ichthus
13 Sport

Fish Stick posted 05-17-2005 01:11 PM ET (US)     Profile for Fish Stick  Send Email to Fish Stick     
Roy,

I do not look at the fin as a solution to poor engine performance, it helps improve the handling characteristics of the boat. Under powered is a different issue.

Even if my engine was running perfect, at max RPM, the Doelfin makes a big difference in how the boat handles, especially with extra weight on board.

Plane faster, less porpising when trimmed up, and more speed. It also improved mileage on my last boat (25' cuddy cabin with 225 Optimax).

Even with the fin, I will be re-proping the boat shortly to get more RPM to match the engine specs.

The only down side I can see are the darn holes you have to drill in the lower unit.

On a side note, every small Whaler in our neighborhood (6 or 7 boats, old and new) has a Doelfin. There is a reason for it.

-Joe

mccomas posted 05-18-2005 09:28 AM ET (US)     Profile for mccomas  Send Email to mccomas     
Roy,

The fin actually looks as though it was built with the motor. The black plastic is the identical shade of black as the Mercury casing and the bolt holes have plastic caps to hide them. If I have time, I'll take some pictures.

Royboy posted 05-21-2005 11:46 PM ET (US)     Profile for Royboy  Send Email to Royboy     
As I understand it, these fins, (or more correctly, foils) lift the engine thus "pushing" the bow down into the water to keep maximum "bite" back where the thrust is happening.

From an engineering standpoint, adding weight to yhe boat is not the answer. Moving weight you already have on board is another thing entirely. The problem with adding weight to get the boat to plane faster, is similar to the classic rocket science dilemna: as you add a bigger engine and hence more fuel to the rocket (to lift the rocket and its payload)it gets heavier and harder to lift, so you add a bigger engine and more fuel, and so on.

A boat failing to come up to planing speed is a function of its weight, the drag of the hull in the water, and the thrust created by the engine. If the thrust of the engine can't overcome the drag and weight the boat will never plane. True, adding mass on the bow end will drive the bow down and let the thrust be applied in the direction that will culminate in planing, but at what sacrifice? Water over the bow occaisionally in the example above, and that was with the NORMAL weight load just redistributed for effect. Imagine cutting the entire wave off because the added weight has exceeded the lift of the hull!!

The foils in this discussion drive the bow down using weight that's already there, namely the hull.

Roy

mccomas posted 05-25-2005 06:45 PM ET (US)     Profile for mccomas  Send Email to mccomas     
Roy, what you are saying is true; however there is a distinct engineering difference between performance (speed, range, endurance, etc.) and handling qualtites (chine walkine, porpoising, deck angle, etc.) Adding weight will almost always hurt performance. It may, however, help with handling qualities.

Some (albeit poorly designed) home-built airplanes, such as the Cozy, have ballast trays in the nose to bring the C.G. forward and improve handling qualities.

Royboy posted 05-25-2005 10:02 PM ET (US)     Profile for Royboy  Send Email to Royboy     
I don't really see the distiction between "handling" and "performance" (and I am an Engineer, by the way). They are two words used to describe the same thing: how the whole package behaves under power. I was tying to say that adding weight to a small Whaler like a 13 footer to improve the boat's handling(performance,behaviour,whatever) is the wrong direction, and may lead to unforseen consequences. The boat likely handles as good as it's going to with not much more than a 90 percentile pilot, 6.6 gallons of gas, a battery, and a couple of life jackets. This is likely how the design was verified. Once we start adding stuff, especially heavy stuff like a cooler full of fish, another battery, a buddy, etc. is where performance starts to degrade. It simply isn't going to get any better no matter how much more weight you add. Adding weight won't improve the lift of the hull, nor decrease its drag, nor increase the available thrust. Now, shifting the weight of all of your "essential" stuff around may make your situation better than not doing so (by changing the angle of attack), but adding more isn't the logical choice. This is where your doel fin enters the picture (changes angle of attack), or a different prop (increase available thrust), or maybe a skinnier buddy (less mass for the lift of the hull to overcome). Maybe all three, but leave the water jugs to the guys who want extra big wakes.

It might be argued that adding weight will also change the angle of attack, and it will, but at the cost of lift from the hull. Reminds me of a small boat we saw that was plowing badly, due to the skipper's portly wife lounging on the bow. My wife asked me if our boat did that when she was up there. I could answer honestly, or correctly, but not both. I told her, "of course not, silly, this is a Whaler"

Roy

bigjohn1 posted 05-25-2005 10:21 PM ET (US)     Profile for bigjohn1  Send Email to bigjohn1     
"My wife asked me if our boat did that when she was up there. I could answer honestly, or correctly, but not both. I told her, "of course not, silly, this is a Whaler"

Roy, absolutely priceless:-)

mccomas posted 05-26-2005 11:48 AM ET (US)     Profile for mccomas  Send Email to mccomas     
I too am an engineer. My specialty is stability and control and performance of airplanes. The underlying physics for a boat are the same. As long as we keep our whaler at speeds far below the speed of light, Newton's laws still apply.

As you probably know, the period of a dynamical system is directly related to the longitudinal moment of inertia (Iyy*THETA''=M), which will go up with weight added at distances furthest from the C.G. Also, as with an airplane, the furthest forward C.G. results in the lowest angle-of-attack in steady motion (I can explain if need be). As the C.G. approaches the hydrodynamic center of the boat (as it moves aft), the static and dynamic stability is degraded and the handling qualities can become unfavorable (I admit, this is a bit subjective until the C.G moves close-to or behind the HC, at which point the boat can flip over). These two things being said, the handling qualities will be improved with weight in the bow. I agree, speed, mileage, endurance, probably will not. (Note, for non-hydroplaning boats, this is not completely evident. The drag usualy goes up with deck angle faster than it does with wetted area. As a result, balast to reduce the deck angle *may* reduce the overall drag on the boat. For a well designed hull, which most boats have, this is probably not the case, but who knows!).

I have demonstrated the improvement in handling qualities by adding and removing a passengers from the front of the boat. Really pissed off my passenger as she had to wait for me at the dock :)

This is all a moot point for me, the handlinq qualities issues are fixed with the Sting-Ray hydrofoil. Thanks all for your input!

Royboy posted 05-26-2005 01:14 PM ET (US)     Profile for Royboy  Send Email to Royboy     
Your explanation is excellent, and I couldn't agree more. What's important to remember is that the angle of attack change as the weight in an aircraft moves forward actually helps the craft fly better (up to a certain point). The plane gets more lift than the resulting drag presented by the increased area presented to the slipstream. But in a boat, the increase in drag is in opposite proportion to the amount of lift (no real change)caused by the increase in angle of attack. So the drag increases, but the lift doesn't. Needless to say, there is a plane at which the boat is a submarine when the angle of attack is too great from too much forward weight with no possibility of recovery. This is magnified by the presence of waves, somthing an aircraft doesn't have to deal with.

All of this is of course, academic. The real problem is in diplomatically telling your wife to move her mass forward in vehicle to move the CG without insinuating that she's "ballast".

Roy

mccomas posted 05-26-2005 05:02 PM ET (US)     Profile for mccomas  Send Email to mccomas     
I love it!

They really get insulted when you tell them to wait at the dock so that you can go a few knots faster :)

Royboy posted 05-26-2005 09:45 PM ET (US)     Profile for Royboy  Send Email to Royboy     
I may have married the perfect girl; if it's taking too long to get on plane, she instinctively moves to the middle seat, which usually does the trick even though there's really not much to her.

I was poking around at Boat U.S. today and checked out the "Stingray Jr." fin. Looks pretty heavy duty, and it's not nearly as obtrusive as I had expected. I may be bolting one of these on soon. Probably right after my warranty expires this July.

Thanks for not getting in a twist over our dialog here, mccomas, you're a gent. Sometimes these things (threads)can take on an attitude of their own, regardless of intent. I'm glad you stuck with this; I'd be lying if I said I didn't learn anything, and it really helped me to think it all through. Also nice to know some others have tried the expensive route (billyc) and it didn't do the trick. I guess the saving grace there is that SS looks so nice. Anyway, thanks all.

Roy
Ichthus
13 Sport

mccomas posted 05-28-2005 11:52 AM ET (US)     Profile for mccomas  Send Email to mccomas     
Roy, so true. We are all on this forum because we share something in common and would like to share our thoughts and experiences. You too are a gent, happy boating!

Royboy posted 05-29-2005 08:42 PM ET (US)     Profile for Royboy  Send Email to Royboy     
Stingray's just went on sale at West for $39. Looks like I'll get one sooner than anticipated.

Roy

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