Do I Need More Power?

[Jungleboat]

Hi, following my last adventure in Borneo, repairing an old 19ft V hull cabin boat I'm gonna do it again!

This time I've found another old mangy wreck in the grass but a 23ft by 7 or 8ft version. This one does not have such a deep V hull as my current boat. See pic



I'll be completely stripping it down, removing the floor and replacing the stringers and transom. While renewing the cockpit interior I'll keep the weight down, as I want room to move around, rather than lots of cubby holes etc.

My current boat is quite slow, mainly because of it's deep V hull - even on plane it's chewing through the water. See 2nd pic



Now that boat is using a Johnson 90hp (about 30 years old). It's slow and heavy on fuel, considering it's just a little 19ft boat.

In contrast the "new" boat, while a lot bigger, maybe even twice the weight, is a lot more shallow on the V.

My first question is what would happen if I stuck my Johnson V4 90 on there? Would that get it on plane or would it just crawl at displacement speed?

I've also been offered the chance to buy a 130hp Honda 4 stroke, which looks around twice the weight of my Johnson. That also needs repairing but presuming it was working OK, how would it go with that?

One clue - but considering the lack of real expertise around here it might not be - the previous owner apparently used a 150 hp engine, presumably a 2 stroke, and only got "20 knots" out of it.

I wouldn't be in the slightest bit surprised to find said previous owner was using the wrong prop, the engine was not running properly and/or they had 8 people on it... Or not?

Now I know with power you need 4 times the power to go twice as fast, and as such there won't be as big a difference between the 90, the 130 or the 150 as it might at first seem.

One guy has said I need "at least" 200 hp on there?

Why?

Now, thing is, I want a larger boat because I want to go further out to sea. Right now I only take my little 19 footer about a mile off shore at the most.

Then I get scared

The 'new' boat looks a lot bigger and more capable, so those 5 mile fishing areas are looking possible - but what's this obsession with power about?

I find it weird, as locally they all seem convinced you need huge power - yet back in the UK I'd see people trundling around the English channel with boats like mine but some little dinky 15hp engine. Not on plane but they'd move along and peeps seemed happy to go sea fishing in them?

Likewise I see 40 foot sailing yachts with lead keels and 25hp engines? Again they obviously don't get up on plane like a speedboat but they can move around at sea, right?

So do I somehow *need* massive power for the sea or is it just desirable, nice to have, "get home quickly" and all that?

Will the waves be pushing the boat backwards or something, if not enough power?

How about a lower-geared prop? Would that help?

I'm not interested in speed or impressing the fish, I just want something that can take me about 5 miles, maybe even 10 miles, off the coast, will cope with fair sized waves and can handle worse if we get caught in it. For that I don't entirely trust my little 19ft boat, which suddenly seems very small once it starts flumping and thumping around in the waves far from shore...

So what's the minimum power this boat really needs, for use at sea?


Almost any replies or opinions appreciated, as the locals... erm.. they have their own way of looking at things. Most prefer the 'sampan' style fishing boat, which is completely flat at the stern, for speed and economy. I'm far more interested in safety than speed/economy.


Thanks!


JB

 

[Silvertip]

Re: Do I Need More Power?

You answered your own question when you said "Will the waves be pushing the boat backwards or something, if not enough power?" While the weather may be calm when you are five mles offshore, things get ugly in a hurry and you may need that extra power to make any headway. Not having it means you perish and become fish food. Now how is that for impressing the fish as you also say. When boating big water you absolutely must plan for the worst -- not what you can just get by with under the best of conditions.

 

[Jungleboat]

Re: Do I Need More Power?

OK, thanks.

That explains why I need 'enough' power but just what is enough for such a boat?

Is there some kind of formula, such as 'thou must be able to hit 30 knots on a calm day, else you don't have enough power for the sea' kind of thing?

Does 20 knots out of a 150 hp engine on a 23ft boat sound right to you?


Cheers,


JB

 

[ezmobee]

Re: Do I Need More Power?

You'd want a 150+ on that 23' which is a V6. You MIGHT get by with a 140 V4 but I doubt it. The 90 won't plane it.

 

[Jungleboat]

Re: Do I Need More Power?

OK... so 200hp does sound about right.

Mmm.

Presuming I could find such a beast of an engine locally, what would be the minimal size for a back-up (spare) engine? Something that could push it along at displacement speed, should the main engine die for any reason? Or should I try to find 2 100hp engines?

Actually the favorite local engine seems to be the Yamaha 85 - would 2 of those be enough? That would probably be more affordable than the silly money that big engines go for around here.

Alternatively I have heard of a guy with a 150 4 stroke... Do you think that boat could handle the weight of 2 such 4-strokes? Or would that be too heavy on the transom?

Thanks again



JB

 

[Sea Rider]

Re: Do I Need More Power?

Why don't you test your actual engine at wot with a tacho and see if actual rpm's are at least at middle working parameters for that current prop. Check engine rpm specs. Anyway in extreme choopy seas planning a boat could be dangerous. It's your final decision if having an engine that planes properly that boat investing fresh money or remain with same engine correctly propped for just cruising at non planing purposes. If remaining with actual engine, could add a 25/30 HP as a aux engine.

Happy Boating

 

[Jungleboat]

Re: Do I Need More Power?

Sea Rider, both the boat and engine are in need of repair; I'm simply thinking of buying them at present and wondering if they would be economically viable and suitable for what I want to use them for.

I cannot test anything for now, unless you mean my current setup, the 90hp on the 19ft V hull? That is running OK, though the boat's hull needs a good clean. The worse I've found with that engine is that once, coming back into the bay and going with some big waves after one of the four cylinders failed, the boat was slowing right down as waves actually over-took it.

You'd feel it losing speed as the wave went below and the boat ended up trying to go uphill - but then it WAS only running on 3 pots. On 4 it could easily ride over such waves.

I'm happy enough with my current little boat, for near-shore. It's heading further out that makes me want a bigger boat...


JB

 

[sschefer]

Re: Do I Need More Power?

Having two motors is often a wise option but each should be powerful and reliable enough to get you out of danger should you encounter it. Twin 150's would seem to be a good choice from what I've seen others do. That would equate to about 800lbs of stern weight. I think you might want to do a builders launch once you get to a floatable point.

A builders launch is where the builder launches the hull and using weights, positions them in the boat to verify his calculations. It's during this test that you make adjustments as to where you position items for optimal loading. You may find that 800lbs is too much for the boat and that a more powerful single engine is the best solution.

The idea is to test before you buy and save yourself money and grief.

 

[Sea Rider]

Re: Do I Need More Power?

If wanting to remain with actual boat/engine combo and have a extra larger boat, it's a different story, thought you wanted to swap your 90 and used it on the larger one. 2 Yams 85 placed side to each other won't be equal to a single 170 HP engine, will have slight more top end speed, better torque & hole shot and one being the aux of the other and that's it.

Happy Boating

 

[Jungleboat]

Re: Do I Need More Power?

See, here's where I get confused...

This is the 30ft, not 23ft, version of my Yamaha Escort boat:

http://www.mudah.my/Escot+Boat-10632923.htm?last=1

That has to be significantly bigger and heavier than the 23ft boat, and if that's the same as my Escort it's a deep V right through the stern. I'd guestimate it at 4X the weight of my 19ft foot boat - yet this only has a 200 HP engine?

If 130 isn't enough for a semi-V 23ft, how the heck is 200 enough for a deep-V 30 footer?

Here's a 24 footer, also with 200 hp, classed as a 'speed boat' and claiming 45... something? I dunno, kilometer per hour, miles, knots? He's put '(L)'... Borneo, see?

http://www.mudah.my/Speed+boat-12161222.htm

*scratches head*

So if I were to make my existing boat 4ft longer, 1 foot wider, reduce the depth of the V hull to a semi-V, then boost the power from 90 to 130, that's too slow?

But a 30ft boat with a deep V can go OK with only 200hp?

Or should I just accept that 30ft Escort is seriously underpowered?


Ah, it's confusing.




JB

 

[Chris1956]

Re: Do I Need More Power?

Jungle, I am surprized your 90HP motor will not plane that 19 footer. I think it should plane it and push it at least 20 knots. Are you sure the motor is running properly?

I would think that 130HP Honda would plane the 23 footer. I would not expect blazing performance, but you should see 20 knots or so.

 

[Jungleboat]

Re: Do I Need More Power?

Chris, I must have mangled my writing somewhere, my 19ft boat does indeed plane, it just never planes as cleanly as some boats due to the V hull.

The locals mainly seem obsessed with speed and more speed. The vast majority of local boats are like this one:

http://www.mudah.my/Boat+Fiber-12061221.htm

Although only around 1/3 have cabins.

That design is very fast. A 25ft version with a Yamaha 85 will hit 38 knots, stick a 150 on there and it's a rocket ride. Thing is, that design is just done to death, with dinky little 10 footers and boats of 38 feet all sharing the exact same shape and proportions!

Now part of me figures they must know the local waters and conditions, and thus this is the honed and refined result of years of experience, right? But in truth I think it all comes down to speed and economy, as they'll roar along happily on plane with a 30 or 40hp engine.

Now I'm told such boats are fine for the sea, yet most are only about 5ft wide, even the really long ones may be only 6.5ft or so. That just doesn't strike me as safe. Fast, sure but safe? At sea?

So when they say I need 200hp, is that simply to go as fast as those long boats or because I actually need that just to chug along through heavy waves?

I find when I take my own boat out I can happily plane on the way out, yet coming back as the waves pick up means a much slower slog, just riding up and through the waves at little more than walking pace. That's fine, providing I have enough fuel on board.

In fact that's one of my biggest complaints with the 19 footer, that I have to cram so much fuel (a 45 liter tank plus four 20 liter containers...) onto such a small boat, as my jetty is 10 miles from the coast. I don't mind the expense of the fuel so much, just that there's not much room left in the boat...

Overall it just seems so much more sensible to get something bigger - but a 200hp engine around here is serious money. I can buy that boat cheap, I can repair it reasonably cheaply but if I have to spend 30,000 ringgit on an engine as a minimum it's a no-hoper.



For that kind of money I could buy a new boat like the one in the ad, and have the fun of 70 knots on calm water. But are they really safe at sea, when so narrow and the sides so low and the hull completely flat towards the rear?


JB

 

[Home Cookin']

Re: Do I Need More Power?

Selamat pagi
many issues, many questions.
First, forget what they do in merry old England, on quiet canals with extremely expensive petrol. You will be putting your boat out to an entirely different set of conditions, with greater safety concerns. Your better point of reference are your local boaters (fishermen and transport) excluding the crazy ones. Also disregard how sailboats are rigged when it comes to OB's; they are just auxilary.

Sufficient power is a safety issue, whether it's a 14' jon or a 30' center console, when you boat where there are weather, waves and current. Do not cut corners, although you don't need the top end of power. You do, however, need speed as well as power, to return to safety before the weather gets dangerous.

If you can't find your brand look around on the web for something similar in salt water fishing sites, etc. to see how they are rigged. Usually on a 19 you see 115 hp, but range from 90-150.
I have a 21 deep V CC with a 150 which does fine, wouldn't want less, 175 may be better, 200 overkill. Similar boating conditions as yours, minus the arak. So for a 23, I wouldn't do less than a 115, would prefer 175-200, even higher.

Since you mention the need for a back-up, either get twins (and I don't know if 2x100hp = 1x200 hp) or a kicker 15-25. really, a kicker won't be safe in storm conditions, but will get you home in flat conditions, so be realistic about your needs and purpose. If petrol is an issue there, the kicker can be used while fishing.

Jalan jalan

 

[wagnerz]

Re: Do I Need More Power?

You are using 125L or approximately 31 gallons of gas on a 90hp outboard. How far are you traveling? That seems like a lot of gas.

 

[Jungleboat]

Re: Do I Need More Power?

Well I didn't come here to ask questions and then disregard the answers but I think the overall best option for me would be 2 x 85, or 2 x 115's if I can get/afford them.

That gives me a redundancy/backup, which I don't have on my current boat, and at 170 or 230 hp should be enough to push the thing in the direction it's told, even with high waves.

It even gives me the option of poodling around on one engine in the near term, then heading further out to sea when I can get a 2nd

It does seem the 130 is probably a bit under-powered for venturing further out, much as I love the idea of a 4-stroke...

Once again the tough love found here is appreciated


Home Cooking - Selamat jalan juga



JB

PS Regarding fuel consumption, on the river (which can be surprisingly choppy) my 19 footer gets about 1.6 miles per gallon, though I'm told that's quite normal for a boat?

 

[dazk14]

Re: Do I Need More Power?

1st - something is wrong with the 19 footer. Barnacles on the hull, damaged or incorrect sized prop. What are your WOT rpm's. What is the compression of the motor - is it worn? You should see about 120psi all holes. That boat should run low 30+ easy.

Home cookin gave you some solid input and a properly pitched 115HP would push that boat along nicely. With that shallow vee at the stern you don't need a ton of power.

Since you already have the 90hp and - if - you can get the 90HP running well and showing good compression numbers - that might work adequately as well. Again, it would need to be properly pitched.

Note: the shallow v boat will take less hp to plane and be more comfortable in rough seas at ~20MPH max.

a 10HP or 15HP setup with a high thrust prop would troll nicely and get you home in an emergency. Even the High Trust 8HP model yamaha would work.

Good Luck!

 

[Chris1956]

Re: Do I Need More Power?

A 25 foot boat, like in the picture would do 38Kts with an 85HP Outboard? Is that what you said? I find that surprizing. Is it made of balsa wood and canvass?
The beam on a 19-23 footer is usually 8 or 8.5 foot. 25 footers can be 8 foot, which is max for trailering purposes, but lots are wider than that.

On that 23 footer, I think a single large OB, plus a kicker if you think it necessary, for getting home after main engine failure.

Your 19 footer suffers from too small of a main gas tank. It should have a 50 Gal (200 L) tank in it. That would be all you would need to have a range of about 100 Mi.

 

[Jungleboat]

Re: Do I Need More Power?

Chris, the local boats are indeed fast.

It's not so much their weight, though I'm told a cabin slows them down quite a bit, but their long, thin and skinny flat-bottomed hull. My impression is they haven't changed the design since they had to row them, so yes, stick a 40 horsepower engine on there and they fly.

85 horsepower Yamaha 'Enduro'? Wheeee!

I thought at first maybe the locals were confused between knots and kilometers and yes, the non-boating types often will be - but the boaty types are talking knots.

Tell em you have a boat and they'll ask the horsepower. '90..'

"19?"

"No, 90, Johnson V4."

"Oh, 90 lah!? Very fast lah! 50 knots?"

"Erm.. no, about 20 or so..?"

"Wha'?"

And thus begins the process of me trying to make shapes in the air with my hands, while explaining the concept of a relatively short boat with a V hull, as their eyes glaze over...

My own boat is relatively narrow at only around six and a half feet wide and yep, I know more modern things such as Bayliners will be around 8ft, or even wider if they won't be trailered.

That's why I refuse to go to sea in a 5ft wide local boat

On the other hand I know (some) Americans think nothing of sticking a 5.0 liter 300hp engine onto a 16 x 8 foot boat that looks like someone turned an SUV inside out...

Regarding a 200 liter fuel tank, where would I put that on a 19x6 cuddy cabin, complete with live baitwell? In fact I glassed over the inlets for the baitwell and now use its 3 compartments for fuel containers. That was the largest tank the local boat shop had by the way. He did suggest I could fiberglass my own, which I consider on the same level as DIY heart surgery...

Ah, Daz... WOT RPMs? Compression pressures?

Thank you for the chuckle

Here a 'compression meter' means sticking your finger down the spark plug hole to see if it can blow it back out again? A 'moisture meter' means punching the hull before sniffing it and a revcounter is one of those things those mysterious round holes in steering boxes are for, right?

Put it this way, when asking a local "boat mechanic" about the compression in my Johnson he assured me that if the compression were "gone" then "not start at all". There ya go, it's purrfect!

Regarding the necessity of a kicker or spare engine, absolutely. One awesome thing about this place is the lack of regulations. You know what kind of license, training, certificate, rating, insurance or whatever you need to head out in a boat here?

None whatsoever.

In fact the only regulations I've found that anyone takes seriously are you must carry a fire extinquisher and navigation lights at night. That's it, though you do need a license for *commercial* fishing.

But it also means rescue services? What rescue services?

If you're outside of cell range to phone-a-friend then you're &*&^ out of luck. Try not to drift over the Indonesian border as they're trigger-happy.

I spent a long time last night reading through various threads, here and elsewhere, about the comparative virtues of twins versus one big solo. I'm still somewhat on the fence, as there seems to be good arguments on both sides.

My leaning towards twins mainly comes down to the back-up/spare thing plus sheer availability. Any 150hp or bigger outboard locally is likely to be extremely expensive and/or have something wrong with it, whereas the 85 Yam is pretty common. Not cheap but at least you're not haggling with the only person on the island who has one for sale.

If I can find a good 175 or so single that's affordable then I'll go for that but I don't have much hope of finding such a beast, not without a 2nd mortgage.



JB

 

[Chris1956]

Re: Do I Need More Power?

JB, most fuel tanks would be under the floor (deck). My 19 foot Searay I/O had a 35 Gal tank (140L). My 21 footer has a 63 Gal tank. Some 21 footers have 100Gal tanks. You have no room under the deck of the 19 footer?

 

[Jungleboat]

Re: Do I Need More Power?

Under the deck?

*JB adopts a comically puzzled look, his eyebrows waggling like crazy*

That would be the same deck I replaced awhile backs, right?

The same super heavy-duty ply soaked in resin and fiberglass floor that makes me itch just thinking about it, even now..?

Arse.

Rip up that floor and.. nooo!

Just no!


Hey, what do I care, I'm changing boats anyway

Phew! Had me worried there...


Good to know though, as this 'new' boat will have all its interior gubbins ripped out.

*Note to self - build/fit a fuel tank under the floor*



Cool. Cheers



JB