2003 130 Model with 40-HP

Optimizing the performance of Boston Whaler boats
Shoeman
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2003 130 Model with 40-HP

Postby Shoeman » Mon Jun 24, 2019 9:12 am

To a year 2003 130 model with a 40-HP four-stroke-power-cycle engine, I have aded a fishing trolling motor and another battery. Now with two people the 130 model is slow to accelerate to plane.

The propeller has the appearance of having a 10.5-inch diameter and a 14-pitch, and the propeller may be the original propeller.

The engine accelerates to slightly more than 5,000-RPM at full throttle.

Q1: should the propeller be changed to a new propeller with 13-pitch?

Q2: should the propeller be changed to a new four-bladed propeller?

Q3: should the propeller be changed at a new four-bladed propeller with 14-pitch?

Thanks for advice.

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Phil T
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Re: 2003 130 Model with 40-HP

Postby Phil T » Mon Jun 24, 2019 11:10 am

You have added about 75-lbs of weight to the boat, some of which is in the stern. This affects performance.

Before spending any money, do some experimenting.

With the trolling motor and battery installed, move the fuel tank forward (may need to buy longer fuel line). You want to see what impact shifting weight forward has on performance. Many members have moved their fuel tanks or batteries amidships.

If you change props you will want to address engine mounting height too.

Report back on the results of shifting weight forward as well as your top speed and RPM's.
Member since 2003
1992 Outrage 17, 1992 Evinrude 115

Shoeman
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Re: 2003 130 Model with 40-HP

Postby Shoeman » Mon Jun 24, 2019 2:01 pm

Thank you, sir.

I have since contacted a few propeller places concerning [the sluggish performance of the 2003 130 boat with added trolling motor and battery].

Yes, some of the weight needs to be shifted toward the bow , perhaps to be under the front and mid seats.

My intentions were to reduce drilling any additional holes into the hull.

Again Thanks.

v12mac
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Re: 2003 130 Model with 40-HP

Postby v12mac » Wed Jun 26, 2019 6:26 pm

What brand and model is the 40? You need to know the manufacturer’s recommended RPM range.

flymo
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Re: 2003 130 Model with 40-HP

Postby flymo » Sat Jun 29, 2019 8:52 am

The answers to Q1, Q2, Q3 are maybe, no, and no.

You clearly need a different propeller, but to make a recommendation we need to know the maximum RPM of your engine, and also what speed and RPM you can achieve when running with a light load.

You absolutely do not want a four-blade prop, no matter what pitch, on a c.2003 four-stroke-power-cycle engine. The extra blade area will inhibit your acceleration even further.

I would be inclined to get a good, stainless steel three-blade prop with relatively low blade area, possibly something like the PowerTech SCD-3. Pitch is a guessing game without more data (and still a bit of a guessing game, even with it). If you go with the PowerTech, they let you trade in within 30 days if you need a different pitch. If [recommended] engine maximum RPM is 5500, I'd start with the 14-pitch in the SCD-3, and if it's 6000 I'd go with 13-pitch.

Oldslowandugly
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Re: 2003 130 Model with 40-HP

Postby Oldslowandugly » Sat Jun 29, 2019 10:10 pm

Normally a 40-HP engine would be a screamer on a 13 footer. As stated, you have added a lot of weight to a small boat. A 40-HP engine is big and heavy to begin with and being a four-stroke makes it even heavier.

I recommend first to move weight around.

If moving weight around does not help the performance, then I recommend a propeller change.

You want less pitch to move weight. But not too much less or the engine may over-rev.

Some propeller manufacturers jump two inches of pitch between models. SOLAS propellers change an inch at a time.

If you have a friendly dealer he may let you test propellers until you find what you need to get into your engine's specified operating speed range.

Shoeman
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Re: 2003 130 Model with 40-HP

Postby Shoeman » Mon Jul 01, 2019 6:29 pm

Thanks.

[With the four-blade 13-pitch propeller the 2003 130 boat with added trolling motor and battery] actually gets on step much quicker with two people and gear [than it did with the three blade 14-pitch propeller]. Before, the boat took 30 to 40-seconds to plane, and now [the boat is on] plane in around 10-seconds. The boat will stay on plane at 15-MPH, where before the boat would try to fall off.

18-MPH at 4,200-RPM

I haven’t run the engine at full throttle yet. I think the boat speed will be 25-MPH.

flymo
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Re: 2003 130 Model with 40-HP

Postby flymo » Tue Jul 02, 2019 7:26 am

That's great. You're giving up some acceleration and top end with a 4-blade, but sounds like you have something that meets your needs and that's what matters.

jimh
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Re: 2003 130 Model with 40-HP

Postby jimh » Fri Jul 05, 2019 8:10 am

flymo wrote:You're giving up some acceleration and top end with a 4-blade...


There is only one speed data point provided for the new propeller, and it was not at full throttle. I don't see the basis for the conclusion that top speed has been lost with the propeller without actual data showing that occurred.

There is data about acceleration onto plane, and the new propeller accelerates onto plane faster. This data contradicts the comment that acceleration was lost with the propeller.

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Re: 2003 130 Model with 40-HP

Postby jimh » Fri Jul 05, 2019 8:23 am

Shoeman wrote:[With the four-blade 13-pitch propeller the 2003 130 boat with added trolling motor and battery]...will stay on plane at 15-MPH, where before the boat would try to fall off...


Generally the ability to maintain plane at a low boat speed depends on the ability of the engine to produce enough power at low engine speeds. The usual reason a boat falls off plane is the engine can't maintain the needed engine speed at that lower RPM range, and the engine decelerates, causing the boat to decelerate and come off plane. If the engine has enough power at low engine speeds, almost any boat can be kept on a low-speed plane.

A four-blade propeller might produce more stern lift than a three-blade propeller of similar design, and added stern lift could improve the ability for the boat to reach plane at low speeds. The reduction to 13-pitch from 14-pitch will help the engine accelerate to a higher engine speed, which may but the engine into an engine speed where it can develop enough horsepower to maintain engine speed at low boat speeds. Small displacement four-stroke-power-cycle outboard engines are somewhat notorious for lack of power at low engine speed ranges.

The original 13-foot classic Boston Whaler hull had some hook in the hull bottom running surface at the stern to help the boat reach plane at low speeds and stay on plane at low speeds--more or less a built-in trim tab mechanism. I suspect the 2003 130 hull probably does not have a running surface with a hook near the transom, and this probably affects the ability of the hull to get on plane at low speeds, and particularly with added weight at the stern in the form of a trolling motor and added battery.

flymo
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Re: 2003 130 Model with 40-HP

Postby flymo » Fri Jul 05, 2019 4:22 pm

jimh wrote:
There is data about acceleration onto plane, and the new propeller accelerates onto plane faster. This data contradicts the comment that acceleration was lost with the propeller.


Jim, I did not comment that acceleration was lost, but rather that the original poster was giving up some acceleration and top end with a 4-blade, relative to what might have been achieved with a 3-blade. We don't know that because he hasn't tried a 3-blade.

If the combination of better acceleration and ability to hold plane at the lowest possible speed were what was desired, I would have made a different recommendation. I have no doubt that a low pitch 4-blade would meet those goals on the 130, and I'm genuinely glad those goals seem to have been realized. However, the original post asked only about advice on improving acceleration, and in general, 3-blades will do better on boats like this 130, which as a 4-stroke is somewhat lacking in midrange torque and thus can benefit from an easy-spinning prop.

I am guilty of thinking that Shoeman cared about top speed, although he was silent on that. He has not done a speed run yet, but I think his guess of 25 MPH is probably about right. So he's giving up a significant amount of top end in favor of acceleration when heavily loaded and ability to hold plane at low speed.
Last edited by flymo on Sun Jul 07, 2019 6:07 am, edited 3 times in total.

jimh
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Re: 2003 130 Model with 40-HP

Postby jimh » Fri Jul 05, 2019 4:42 pm

FLYMO--thanks for the further explanation.

Shoeman
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Re: 2003 130 Model with 40-HP

Postby Shoeman » Fri Jul 05, 2019 8:35 pm

Finally something logical!

It was never about top end, since it wasn’t my goal! My only concern was the waters we cruise that a following Sea would come over the transom !

If one can’t compensate for the speed of the in-coming wake.....

Therefore I needed instant acceleration to stay in front of the wakes or waves. Yes the new prop did allow that!

Still too much weight in the back, especially with me working the trolling motor solo

Love the prop, it will get me out of trouble! Been boating too long... bought this little thing for the Keys during the Winter months and allow fishing Lake St.Clair..

32 smiles today! Got her tied up the Sue Me!

Sorry about the angry post prior.... acceleration wasn’t a goal... it was something needed to not get swamped over the transom!

marineusa
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Re: 2003 130 Model with 40-HP

Postby marineusa » Wed Jul 24, 2019 1:26 pm

Maybe your battery is screwed up. You need the right battery to produce power at low speed. You should look for a better battery. But I do like the idea of swapping out the prop.

biggiefl
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Re: 2003 130 Model with 40-HP

Postby biggiefl » Wed Jul 24, 2019 1:55 pm

"You need the right battery to produce power at low speed."

Can you show me an article or something that backs this up outside of DFI 2 strokes?

I run my 40hp 4S Suzuki with a garden tractor battery and she performs just like it did with a regular one but 40lbs lighter.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall. :roll: