Help with atypical motor setup

[LDUBS]

Don't be upset if you get a little resistance to your ideas. Thinking men debate all the time, and the result is often a thoroughly thought-out end product.

Stay cool, and don't feel threatened or offended. Listen to everyone. There is a huge amount of experience and knowledge here, so chew on suggestions before accepting or discarding. Once you decide on a course of action, the folks here will respect it and will try to help you reach your goals in the smartest way possible.

X2 on this -- good stuff.

And, you will find we are very good at spending someone else's money on their project!! Hahaha.

 

[airshot]

Sorry. I had another senior moment. I meant to say splash well. I was talking about a jump seat to the side of the splash well.

Glad I am not the only one that has those " moments" !!!

 

[PunkR0ckz]

My initial thoughts are that hanging 525lbs off of that transom and then cutting a chunk out of it is a recipe for a quick trip to the bottom of the lake.

I would think the thing to do would be to ditch the V4 (they are good motors but very thirsty, heavy, dinosaurs) and find a more modern 60-70hp 2 stroke triple. This will cut almost 200lbs off of the transom. Mount it in the center conventionally, and your kicker to either side.

My reasoning there is that you are not going to get much for speed/performance out of the kicker no matter what, there is no advantage to mounting it in the center, and doing so would risk it not handling well with the primary outboard (which as you've stated, when you need it, you need it.)

As for your transom door, I think it is a neat concept, but I don't see it working well on that boat. If you were able to make it work, that area would likely be under water all the time, with the weight on that transom you are likely to only have ~10" of freeboard. I have only ever seen gunwhale doors on large boats where the floor/deck is above the waterline.

I'm sorry, I might've explained it poorly partly due to me being a French Canadian.

As I have back problems, I'm unable to lift my legs very high.

With the current setup, which is just a floor, I have to use a small step stool to get in or out of the boat without worsening my back pain.

In other words, I wanted to make a small step (about 8 inches high) near the transom and then cut open the top of the splash well that is above the height at which the outboard sits on, and replace that part with a door.

If you were to look at it from inside of the boat, to go onto the swimming platform, you'd have to step on a "stair", open the door, raise your legs above the remainder of the height (about the same height as the "stair") and then drop your feet on the swimming platform. The "door" (without having measured it, as it is stored for the winter) would probably be about 12 inches high. I'm not able to describe it better at the moment, but technically there shouldn't be any water coming in at any time, unless it goes above the splash well altogether, which would then be very high and very bad and then, I'd need the 115 v4 heheh

Hopefully this explanation makes more sense now? I could try to find a picture of a similar setup online if need be.

(Edit; I quickly looked online, and the setup I was thinking about was something similar to the Quintrex cruiseabouts, if you take a look at this specific video, at 1:50 he shows how the door works, how big it is etc... if you look at the bottom of the door, its just above the level where the Etec sits on the transom... that was the same idea I was wanting to do with mine, as anything above that line should technically be always dry, I'd make sure the door is lockable and seals properly, and it would be a swing open, not a drop down... Here's the video link; )

 

[Billy H]

I'm sorry, I might've explained it poorly partly due to me being a French Canadian.

As I have back problems, I'm unable to lift my legs very high.

With the current setup, which is just a floor, I have to use a small step stool to get in or out of the boat without worsening my back pain.

In other words, I wanted to make a small step (about 8 inches high) near the transom and then cut open the top of the splash well that is above the height at which the outboard sits on, and replace that part with a door.

If you were to look at it from inside of the boat, to go onto the swimming platform, you'd have to step on a "stair", open the door, raise your legs above the remainder of the height (about the same height as the "stair") and then drop your feet on the swimming platform. The "door" (without having measured it, as it is stored for the winter) would probably be about 12 inches high. I'm not able to describe it better at the moment, but technically there shouldn't be any water coming in at any time, unless it goes above the splash well altogether, which would then be very high and very bad and then, I'd need the 115 v4 heheh

Hopefully this explanation makes more sense now? I could try to find a picture of a similar setup online if need be.

(Edit; I quickly looked online, and the setup I was thinking about was something similar to the Quintrex cruiseabouts, if you take a look at this specific video, at 1:50 he shows how the door works, how big it is etc... if you look at the bottom of the door, its just above the level where the Etec sits on the transom... that was the same idea I was wanting to do with mine, as anything above that line should technically be always dry, I'd make sure the door is lockable and seals properly, and it would be a swing open, not a drop down... Here's the video link; )

I’m trying to follow this thread but now I’m totally confused. I looked at the video. I don’t think you’re comparing apples to apples . Is this not a picture you posted of your transom?
Wish you the best on whatever you do. I’ll be checking back as progress is made.

 

[thill]

I'm just starting to read this post more carefully.

Regarding your first question- should you offset your 115 to make room for the 25 - My answer is NO.

Simply balance the load with your battery and/or fuel tank placement.

I did this with my 18 Starcraft, and it worked great. I HATE only having a single battery in any boat, so I added a Group 29 battery, and moved both of them to the far corner, and it balanced perfectly.

That Starcraft is pretty heavy and stable to start with, so it wasn't much of an issue anyway.

The 25 will push well no matter where it is on the transom. A 9.9 or 15 will push almost exactly the same.

It was suggested to trade out for a 3-cylinder Evinrude 70, but if you want to lighten the load and still keep a good top speed, a 3-cylinder Yamaha or Mercury 90 are good choices, IF you can find one at a good price.

I'll keep reading as I get time and throw my 2 cents into the discussion.

 

[thill]

I'm sorry, I might've explained it poorly partly due to me being a French Canadian.

AAAAHHHHH!!!!! Canadians!!!!!

Ha ha, just kidding. A good friend of mine lives right on the Vermont/Quebec border and loves to go up there. He knows a lot of French, which is surprising, since he seems rather uncultured. A mountain-man type. We are talking about making a trip up there this winter for some ice fishing, and we might pop across the border while up there. Beautiful place!

 

[PunkR0ckz]

I'm just starting to read this post more carefully.

Regarding your first question- should you offset your 115 to make room for the 25 - My answer is NO.

Simply balance the load with your battery and/or fuel tank placement.

I did this with my 18 Starcraft, and it worked great. I HATE only having a single battery in any boat, so I added a Group 29 battery, and moved both of them to the far corner, and it balanced perfectly.

That Starcraft is pretty heavy and stable to start with, so it wasn't much of an issue anyway.

The 25 will push well no matter where it is on the transom. A 9.9 or 15 will push almost exactly the same.

It was suggested to trade out for a 3-cylinder Evinrude 70, but if you want to lighten the load and still keep a good top speed, a 3-cylinder Yamaha or Mercury 90 are good choices, IF you can find one at a good price.

I'll keep reading as I get time and throw my 2 cents into the discussion.

Alright, here is a bit more thinking I did with everyone's input;

According to JD Power, which seems to have a lot of informations in regards to boats;

2006 Mercury 25hp EFI 4-stroke (25ELPT model) weighs 157lbs.
1988 Johnson 50hp VRO 2-stroke (50TLCC model) weighs 218lbs.
Year unknown Evinrude 115hp VRO 2-stroke (115493 model) weighs 265lbs. (I took this information as it is the oldest I could find on the website in the 120hp range for Evinrude, 1974).

As I truly need the 4-stroke, it would weigh either 422 lbs with the 115hp (or possibly more if it is a 120hp from a more recent year, up to 100 lbs heavier, so 522 lbs) or 375 lbs with the 50hp.

Yeah, I think this is what I might do, I might install the 50hp + 25hp on the back of my newly acquired Starcraft Offshore, and I'll put the 115hp on the back of my 1984 Astroglass 154v (even if it could possibly overpower the boat... plaque says limited to 100hp).

However, as far as balancing the hull with other things, I am against that. I would rather have everything centered and symmetrical "à la center console", then weirdly shaped and offset "à la bass boat" (which is why I'm selling my Astroglass, this and the fact a bass boat isn't for me with my back pain).

I guess that if I put the trolling motor and the kicker to the port side, it might offset most of my weight, alongside the prop thrust, if I were to offset by 1" the main 50hp... Would that make more sense ?

 

[flatheadsteve]

A 60hp tohatsu weighs 213lbs..edit to add I'd also strongly consider a bow mount trolling motor. Both for weight distribution and better boat control. One with a remote will allow you to control the boat from anywhere.

 

[Tinny Fleet]

I have this same boat slightly different year and motor (same engine block size). Just the motor is borderline too big for this boat, although I have run a 10 hp kicker on it.

The weight of a 25 kicker on the stern would torpedo that boat with the first wave that came over the transom, IMO. No way would I chance that.

 

[PunkR0ckz]

I have this same boat slightly different year and motor (same engine block size). Just the motor is borderline too big for this boat, although I have run a 10 hp kicker on it.

The weight of a 25 kicker on the stern would torpedo that boat with the first wave that came over the transom, IMO. No way would I chance that.

Basically you're telling me I'm better off with the 50hp Johnson and the 25hp Mercury as a kicker? I mean, it's totally possible it is borderline as is, I haven't had a chance to put it in the water as I'm from Canada and where I go the lakes won't allow it until next season, and there's holes below the waterline.

Do you think, by any chances, you could give me a drawing of your gunwhale caps (the corner ones) if possible? I am missing both of them, I'll have to make both of them and I'd like to have them as close to original as possible. That'd be greatly appreciated!

 

[PunkR0ckz]

A 60hp tohatsu weighs 213lbs..edit to add I'd also strongly consider a bow mount trolling motor. Both for weight distribution and better boat control. One with a remote will allow you to control the boat from anywhere.

I can't buy another 4-stroke. They are very expensive even old ones. Anything above 30hp is past the 5000$USD price point around here, its crazy. So, suggesting a new or used 4-stroke is basically a waste of time at this point. In the future, possibly, but right now... I'm stuck with the 3 motors I listed hehe

 

[MrGiggles]

I'm sorry, I might've explained it poorly partly due to me being a French Canadian.

As I have back problems, I'm unable to lift my legs very high.

With the current setup, which is just a floor, I have to use a small step stool to get in or out of the boat without worsening my back pain.

In other words, I wanted to make a small step (about 8 inches high) near the transom and then cut open the top of the splash well that is above the height at which the outboard sits on, and replace that part with a door.

If you were to look at it from inside of the boat, to go onto the swimming platform, you'd have to step on a "stair", open the door, raise your legs above the remainder of the height (about the same height as the "stair") and then drop your feet on the swimming platform. The "door" (without having measured it, as it is stored for the winter) would probably be about 12 inches high. I'm not able to describe it better at the moment, but technically there shouldn't be any water coming in at any time, unless it goes above the splash well altogether, which would then be very high and very bad and then, I'd need the 115 v4 heheh

Hopefully this explanation makes more sense now? I could try to find a picture of a similar setup online if need be.

(Edit; I quickly looked online, and the setup I was thinking about was something similar to the Quintrex cruiseabouts, if you take a look at this specific video, at 1:50 he shows how the door works, how big it is etc... if you look at the bottom of the door, its just above the level where the Etec sits on the transom... that was the same idea I was wanting to do with mine, as anything above that line should technically be always dry, I'd make sure the door is lockable and seals properly, and it would be a swing open, not a drop down... Here's the video link; )

That makes more sense. Cutting out the splashwell should be no big deal, it does add some rigidity to the back of the hull so it would be wise to design your stair step so that it is tied into the remainder of the splashwell and the gunnel, turning it into a structural member.

 

[PunkR0ckz]

That makes more sense. Cutting out the splashwell should be no big deal, it does add some rigidity to the back of the hull so it would be wise to design your stair step so that it is tied into the remainder of the splashwell and the gunnel, turning it into a structural member.

Yep, as I mentioned beforehand, I'll be making the transom out of 1.5 x 1.5 aluminum tubes, as it is normally 2x 3/4 plywood anyway. In the front, where the splashwell starts, I'll be making a structure with doors and whatnot for my storage, and I'll tie both of them together with tubes too. It'll be one big structure in the end. That's why I'm not afraid to cutout the splashwell and reshape it. I'm just not sure how high (or low) I should go for the door. I'll need to dump it in the water first and see the regular water line, unless someone has a picture for reference straight from the back hehe

 

[PunkR0ckz]

Just found a HUGE deal on FB Marketplace.
A brand new round outboard earmuff, a bunch of brand new in the box stainless steel cleats (6 or 7 of them, according to the picture) and some Bennett Trim Tabs with the pump and cylinders, all for 50$CAD! (40$USD)! That ought to help my build quite a bit. I was missing some cleats, I was using my uncle's earmuffs and trim tabs are always a positive. I think the only thing that is missing is the controller for the cylinders of the trim tab. Even if it is missing the controller, it shouldn't be much of an issue, its just 2 momentary switches and a few wires, so that's no biggie. Hopefully it isn't a scam, girl says she's selling for her husband as they got rid of the boat a few years ago and just found those parts laying around... husband bought them brand new... will see tomorrow I guess!

 

[PunkR0ckz]

Update;

As mentioned yesterday, I found a deal online and I was able to pick it up this morning.

Everything in the pictures was sold for 50$CAD.

Now, with this update comes a new question.

Do you guys think the 25hp 4-stroke could push this tiny Starcraft Offshore 18.5ft decently with the trim tabs and a proper weight distribution?

I am asking this question because I highly doubt I could fit the 50HP 2-stroke Johnson, the 25HP 4-stroke Mercury and the trim tabs.

I know there is a rule of thumb that says anywhere in between 25-40# per HP is "good enough", but I'll be closer to 55# per HP.

Obviously, I don't want to overwork the 25hp 4-stroke. I have driven my uncle's 16ft fiberglass runabout (I believe it weighs around 750#, similar to my Starcraft Offshore) with 3 lead-acid batteries (about 200# at the back), 1 gas tank (about 25# at the back), 3 person (total of 700#, 350# at the back(me) and 350# at the bow windshield), 2 coolers and fishing gear (middle seat), which was about a total of 1800# or so, with a tiny 15hp 4-stroke Suzuki. That thing would barely go on plane because we couldn't distribute the weight better, but it was still moving us along. I'd be about 500# lighter or so, with a motor about twice as powerful and trim tabs... I believe I would be OK, but I don't know if because that would be outside the 25-40#/HP realm, I'd be overworking the motor. I'd like someone else's feedback if possible

Thanks again everyone!

 

[LDUBS]

Another thread caused me to look at a picture of a Starcraft Superfisherman. It has a swim platform which made me think of your post. Here you go:

 

[jethro]

My Sylvan has an aftermarket swim platform. It just gets bolted on. I love it, don't think I can own a boat without one anymore.

 

[PunkR0ckz]

My Sylvan has an aftermarket swim platform. It just gets bolted on. I love it, don't think I can own a boat without one anymore.

Nice setup! What's the width of the transom opening? Seems wider than mine, based on your 150's size Gives me hope I can do it with mine too

 

[jethro]

Nice setup! What's the width of the transom opening? Seems wider than mine, based on your 150's size Gives me hope I can do it with mine too

I'll try to remind myself to measure it when I get home. Beam is right around 100", I know that.

 

[thill]

Do you guys think the 25hp 4-stroke could push this tiny Starcraft Offshore 18.5ft decently with the trim tabs and a proper weight distribution?

No. It's a heavy boat. I doubt it will be able to get it up on plane.

My Starcraft Mariner that had been gutted, so it was only a floor and small side console only did about 25-27 with a Yamaha 60 on the back. Most of those boats run with 70HP+ on the back, from what I've seen.