motor questions for newbie

[X-1hydro]

hi i am currently building a 14 foot X-1 cab-over hydro and was wondering if you have to use a special motor or if the motor has to be a certain type. i am not going to race just want something to zip around in on our pond, well actualy its like a small lake. and i noticed that hydros have a small fin on the left sponson to aid in turning but since im not going to race and turn in both directions at good speed would i be able to just put a fin on each sponsoon or is that not possible? than you ne info would he helpful to get this newbie safely out on the water...sorry to mention the motor i was gonna use is the old 70 horse evinrude off my 1968 hydroswift out in the back, thank you

[Mark75H]

You will probably also find that the design of the hydro is insufficient to float a standard motor. Plan on altering the transom and motor mounting height accordingly.

[X-1hydro]

well here is a pic of the motor i plan on using. so by altering the height of the motor mount do you mean making it so less of the motor is in the water? and if so then how much of te lower unit should hang below the hull but the motor will not have the gray plate on it. here is a drawing of the general shape of the hydro and this boat will be 14 feet long and almost 7 feet wide. any help on ne modifications that will need to be made would helpful as i am buildong 2 of these. oh and would putting matine foam in between the transom frame and number 4 frame help give the back more flotation to help support the motor? thank you

[Mark75H]

Adding foam increases weight and makes the boat lower in the water (not much though because the foam is very light).

I think that boat was designed back when a 120 pound 40 hp was the biggest you could buy. Your 70 weighs about 210 pounds. I suspect your plans call for a 15" transom, you will need to get your motor up to where the top water inlets are even with or above the bottom of the boat; probably closer to 20" from the clamp.

[X-1hydro]

in the plans it specifys a 60-100hp motor be used. if ne one has drawings or diagrams showing what needs to be done that would help. so instead of the transom board being 15" extend it so the height is 20"?

[Mark75H]

You should extend it so it fits your motor.

[X-1hydro]

ok so the three water inlets on the lower unit should be even with the bottom of the ull or a little bit above it. would it be okay if they were somewhat below the bottom if i did it that way?

[X-1hydro]

as much as id like to im only 17 and have a limited budget. my dad built a hydro almost identical to the one i am building when he was in highschool and that is why i want to do this project. but this is the only motor i have access to so i have no choice but to use it

[Mark75H]

You will be much happier if you build the newer type boat with the smaller motor - the design is far superior for a modern electric start motor. It shouldn't take much to find someone who wants to trade a 2 cylinder 60 for your 3 cylinder 70.

If your budget is super limited, you should consider a boat like a Minimost and a very small motor over the X-1

[X-1hydro]

i realize there may be better boats out there but i havent found many plans and the x-1 is the best ive found thus far. as for trading someone motors i have no idea where to look. im in spokane washington but i have no clue. and as for a smaller boat and motor im kinda a big guy and dont know if it will handle me im 6' 3" and 220 pounds. as i said before im not gonna race as i dont have the time or funding just want a fast boat to take to lake roosevelt or pondere' which are huge lakes. does anyone know how stable these design onf boats are? and their stability at high speeds? and what about cornering? i have had some input on these subjects from other sources but ne opinions ar info always helps...thanks