Will this motor work on this boat? 70HP on 18ft fiberglass boat

[randee]

Hi boat experts, I have found a lot of useful topics, but I got a questions I thought you guys would be able to answer for me.

My old 15' fiberglass fishing boat has seen better days. The floor is getting soft and I am confident it's not worth repair. I think the hull is fine, but I have been taking the family out on the river and would prefer a little newer maybe safer ride. The early 80's 70hp VRO johnson is still running fine. I haven't checked compression on it but, when I bought it in 2013, I was told it was recently rebuilt.

I found a guy who has a boat&trailer with no motor for sale for $600. He says it's a 16' but I am thinking it's 18'. It's a jason 1800sf fiberglass boat. He had a 150hp motor on it, although I have seen the same boat with a 115hp mounted on it.

My question is if I put my 70hp on it would it be able to push it?

I don't care about speed as much. I just want to make sure it get's up and planes properly. I don't need to go 30mph. If anyone has attempted something similar I would love to hear about your results. If this does work out I could maybe upgrade motors in a few years when finances allow.

What are your thoughts?

I have attached a sample image of the same model boat and a sample image of the motor. The boat I am looking at is in very rough shape, but I am told the floor and hull are in fine shape. The boat in the image is beautiful. That boat was selling for $2000 with no motor so I was thinking this boat for $600 might be worth it. I think it comes with a trilling motor as well.

Thanks for any input,
Randy

 

[jbcurt00]

If its an 1988 1800SF, its rated for 150hp, and a 70hp is well below the typical 70% of max general rule of thumb for minimum recommended hp.

Depending on load, load balance/distribution, the boat's actual condition (water logged foam weight), prop, how the motor runs (does it reach peak rpm at WOT) And weather conditions, a 70 might or might not get it up on plane.

 

[randee]

Thanks for the info,

Yes, the boat in question is 1,150lbs dry weight with a maximum HP of 150hp according to one site. I didn't know about about 70% rule of thumb, good info.

Looks like my current boat weighs about 500-600lbs. So that is a pretty big difference. I never checked speed on mine, but it seems like it scoots, faster than I need it to be for sure.

Well I might have to rethink my plan, thanks for the info.

 

[jbcurt00]

You could live w whatever performance the 70 gives you.

Might do what you want/need it to. But I bet it woouldnt do it for long, simply too undersized.

The next few months is a good time to buy projects and motors. So if you like the boat amd are up for whatever needs to be done (could need a LOT) to the boat. Buy it now, drop your 70hp on it, use it and keep an eye out for a 100-150hp motor. Then sell your 70hp. Another member recently traded his undersized OB for a larger one, when he found a seller looking to downsize his OB.

Or just keep an eye out for a better package to put your 70 on.

A 16ft aluminum boat would be a good fit for your 70hp. An 18ft tin boat would also do better then a heavy 18ft glasser w the 70hp.

 

[ondarvr]

You said the boat looked rough, and at $600 it may need another $1,500 to make it usable if it's got some rotten wood, so it's a gamble. Also a 70 would be on the edge of not working, maybe too close to the edge.

 

[GA_Boater]

Welcome aboard.

Lets see some pics of the boat your are looking at. No help to see what it may have been or could be. What is it like now? I don't like to hear the boat is in rough shape, but the seller says the floors and hull are in great shape. Sellers are notorious for understatement. Bought a bridge lately?

 

[gm280]

I have to agree. Any boat that is going for a mere $600 dollars has some problems for sure. And since you don't want to refurbish your present boat with the soft floor, I think you would only be trading one problem for another. And like previously stated, a 70 HP on a 150 HP rated hull isn't going to work correctly. JMHO

 

[randee]

You could live w whatever performance the 70 gives you.

Might do what you want/need it to. But I bet it woouldnt do it for long, simply too undersized.

The next few months is a good time to buy projects and motors. So if you like the boat amd are up for whatever needs to be done (could need a LOT) to the boat. Buy it now, drop your 70hp on it, use it and keep an eye out for a 100-150hp motor. Then sell your 70hp. Another member recently traded his undersized OB for a larger one, when he found a seller looking to downsize his OB.

Or just keep an eye out for a better package to put your 70 on.

A 16ft aluminum boat would be a good fit for your 70hp. An 18ft tin boat would also do better then a heavy 18ft glasser w the 70hp.

All good ideas, thanks!

Actually I would love to find an aluminum boat that would take my 70, that's what I have been looking for. I find 16' boats that are reasonable but have a 40hp max, or ones that would take a 70hp but want way too much money for it. My perfect world would be a simple aluminum boat with a console. (The wife refuses to drive a tiller and frankly, I don't find it comfortable.)

I am not afraid to do some minor work. Actually I kind of enjoy it knowing I am putting some sweat equity into it. Unfortunately my boat is just not worth it. It wasn't anything special to start and now with the rotton floor I think it's end of life. It was a VRO, but I got scared and just mix it myself. I think the oil was leaking on the floor and ate away at the coating.

Ya, I that's a good point about trading. I may even trade down. Trade in for a nice 40hp that can mount on a simple aluminum boat. Although I would rather do as you suggested and find a 100-150hp. If I got this boat that is, which I might skip it.

Thanks!

 

[randee]

You said the boat looked rough, and at $600 it may need another $1,500 to make it usable if it's got some rotten wood, so it's a gamble. Also a 70 would be on the edge of not working, maybe too close to the edge.

Understood!

Ya, wouldn't be worth it if I had to invest that much. As far as the details, I really don't care if the paint is faded or window is cracked. As long as I can go out throw a line in or check out the wildlife.

Do you know a good way to test for rotten wood?

Thanks!

 

[randee]

No Title

Welcome aboard.

Lets see some pics of the boat your are looking at. No help to see what it may have been or could be. What is it like now? I don't like to hear the boat is in rough shape, but the seller says the floors and hull are in great shape. Sellers are notorious for understatement. Bought a bridge lately?

As requested my potential purchase and my current boat...

Bought any bridges? no.. but you'd be right in that I could easily make a mistake when buying a boat. Somewhat out of my element here.
I spent a good part of my life on boats, but never spend to much time buying them. Usually small jon boats with a 10hp motor than we took off the boat when were done using it. If there was a floor it was just plywood over the ribs that could be pulled up if it was rotten or we dropped a lure.

I do love my current boat's features. I like the tilt and trim. I especially like electric start. Most of my prev boats were pull start and boy did that suck when you were diagnosing a problem.

Going to look up a way to see if I can inspect wood. Obvoiusly I can take my 250lb foot and see if it gives, but my didn't really have any soft spots when I bought it. I should have known when I saw the floor pedastals were stripped rotated and rescrewed.

Thanks for the input!

 

[randee]

I like this ad of what this boat could look like if it was in great shape. JASON brand read on this forum that it didn't last too long but may have been a decent boat.

 

[ondarvr]

From the looks of it I'd say it will need quite a bit of work, probably stringers, floor and transom, boats don't do well when they're stored outside under a tree. Plus there are other missing parts that will add to the cost. In that condition it's a free boat, if the trailer has any value it's offset by the potential disposal of the boat.

Looks like $1,500 would be on the low side, the very low side.

 

[randee]

From the looks of it I'd say it will need quite a bit of work, probably stringers, floor and transom, boats don't do well when they're stored outside under a tree. Plus there are other missing parts that will add to the cost. In that condition it's a free boat, if the trailer has any value it's offset by the potential disposal of the boat.

Looks like $1,500 would be on the low side, the very low side.

Wow, really?
That didn't seem to bad to me, but you guys would no more about it. He said it was stored in a barn for the last 15 years. Is there anyway to test to see if floor/stringers and transom are bad?
Well, I guess I will keep looking then. thanks for the info...

Like I said I am not afraid of work, but if it would really need those things its too far gone. Maybe I can fine a nice aluminum with a decent motor and borrow some money from the bank.

 

[jbcurt00]

You probably need to go look at several dozens of possible peojects to get a sense of what you see in a few ad pix.

Nothing beats a hands on inspection.

But heres a good check list to follow
http://forums.iboats.com/forum/gene...eeding-help-buying-a-boat-a-buyer-s-checklist

And we can only base our opinion on the limited pix and info you provide. That and seeing thousands of similar project boats posted in the resto forum.

Read thru some of them:
http://forums.iboats.com/forum/boat-repair-and-restoration/boat-restoration-building-and-hull-repair

 

[randee]

I will read through the checklist and check out some posts, thanks for the info!

 

[randee]

No Title

Still trying to find an aluminum boat that will take my 70HP outboard. Found this G3 18', but wonder if my 70HP would be enough to push it. Even though this is aluminum, still seems big and heavy. Would you agree?

The 16' aluminum boats I find have a max rating of 40 or 50 hp. Just not having any luck, but hopefully something will turn up this fall.
Thanks!

 

[gm280]

Don't worry something will show up that you both like and the 70 HP engine will work on as well. Faith, you have to have boat faith. :decision:

 

[randee]

Got to have boat faith! HA! I like it.. I think that aluminum g3 has a maximum of 150hp, so the 70% rule would still be way off. Only thing I noticed is it appears that there was some sold with a 90hp, so I was thinking the 70hp, wouldn't too far off...

I will keep the faith, something will come... and more in my price range I hope. THANKS!